Nabble - Python - tutor

Re: sqlite3 Python25 parameter binding problem with UPDATEplease help

2008-12-02T11:23:02Z

Hello again,

Finally I managed to get it working!

I had to remove [year] braces from the second argument - year. The
reason I used [] was the posts we exchanged recently (7th of November)
about CGI script where it was recommended by Kent that I put [] around
string argument:

Quote
The second argument to execute() is a *sequence* of parameter values.
A string is a sequence of characters, so by passing a plain string you
are saying that each character of the string is a parameter to the
SQL.

Try adding braces around the parameter to make list:
cur.execute("insert into test (name) values (?)", [sPath])

Kent
Unquote

Now the year argument is string so I thought I should do the same
again but it is not working.
The reason is of course is that I am new to python and there are so
many things to learn so the question really is why in this case there
were no [] or () necessary?

Thanks in advance

Aivars

2008/12/2 aivars <aivars868@...>:

> Interestingly, when simply testing like this:
>
> import sqlite3, sys
> sPATH=r'e:\pythonexamples\aivars2.db'
> oCon=sqlite3.connect(sPATH)
>
> cur=oCon.cursor()
>
> oCon.execute("""UPDATE rezerve SET latusaldo = ? WHERE gads = ?
> """,(6000.0,'2006'))
>
> oCon.commit()
>
>
> it works. Therefore I am stuck since it looks like there is something
> wrong in below function.
>
> Thanks,
>
> Aivars
>
>
> 2008/12/2 aivars <aivars868@...>:
>> Alan,
>> Thanks.
>>
>> Ok I should have been more precise and give more code
>> There is what I do:
>>
>> def starpiba(year, month, day):
>> datumsno=str(year+'-01-01') #beginning of year date
>> datumsuz=str(year+'-'+month+'-'+day) #period end date
>>
>> result = (atlikumiBeiguKurss(year, month, day)-
>> atlikumiDienasKurss(year, month, day))
>> ##print result
>> oCon=sqlite3.connect(sPATH)
>> if result<=0:
>> print abs(result)
>> oCon.execute("UPDATE rezerve SET latusaldo =? where gads
>> =?;",(result, [year]))
>> oCon.commit()
>> else:
>> ##print 'aivars'
>> oCon.execute("UPDATE rezerve SET latusaldo =? where gads
>> =?;",(result, [year]))
>>
>> Please bear in mind I am a noob in Python and I write spaggeti code.
>>
>> There is a table in my sqlite database called rezerve which shows the
>> breakdown of a consolidated reserves item in a consolidated balance
>> sheet report (if that says anything to you) by years. For the previous
>> years the numbers does not change since they are already reported but
>> for the current year it may change month by month until reported.
>> Therefore, I wanted to update the numbers for the current year.
>>
>> The above python function works OK.
>>
>> Thanks
>>
>> Aivars
>>
>>
>> 2008/12/2 Alan Gauld <alan.gauld@...>:
>>>
>>> "aivars" <aivars868@...> wrote
>>>
>>>> oCon.execute("UPDATE rezerve SET latusaldo =? where gads =?;",(result,
>>>> [year]))
>>>> oCon.commit()
>>>>
>>>> it throws me the error:
>>>> sqlite3.InterfaceError: error binding parameter 1 probably unsupported
>>>> type
>>>
>>> I assume its the [year] value it objects to.
>>> I'm not sure what you expect SQLite to do with a list as a value, it does
>>> not support a list type field.
>>>
>>>> All works OK when using INSERT with the same parameters.
>>>
>>> Are you sure? You can insert a list into a field?
>>>
>>>> Maybe I should as this question on sqlite list?
>>>
>>> Perhaps but I think it is the list parameter that it doesn't like.
>>> Unless I misunderstand the syntax.
>>>
>>> --
>>> Alan Gauld
>>> Author of the Learn to Program web site
>>> http://www.freenetpages.co.uk/hp/alan.gauld
>>>
>>> _______________________________________________
>>> Tutor maillist - Tutor@...
>>> http://mail.python.org/mailman/listinfo/tutor
>>>
>>
>

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Re: sqlite3 Python25 parameter binding problem with UPDATEplease help

2008-12-02T10:33:20Z

Interestingly, when simply testing like this:

import sqlite3, sys
sPATH=r'e:\pythonexamples\aivars2.db'
oCon=sqlite3.connect(sPATH)

cur=oCon.cursor()

oCon.execute("""UPDATE rezerve SET latusaldo = ? WHERE gads = ?
""",(6000.0,'2006'))

oCon.commit()

it works. Therefore I am stuck since it looks like there is something
wrong in below function.

Thanks,

Aivars

2008/12/2 aivars <aivars868@...>:

> Alan,
> Thanks.
>
> Ok I should have been more precise and give more code
> There is what I do:
>
> def starpiba(year, month, day):
> datumsno=str(year+'-01-01') #beginning of year date
> datumsuz=str(year+'-'+month+'-'+day) #period end date
>
> result = (atlikumiBeiguKurss(year, month, day)-
> atlikumiDienasKurss(year, month, day))
> ##print result
> oCon=sqlite3.connect(sPATH)
> if result<=0:
> print abs(result)
> oCon.execute("UPDATE rezerve SET latusaldo =? where gads
> =?;",(result, [year]))
> oCon.commit()
> else:
> ##print 'aivars'
> oCon.execute("UPDATE rezerve SET latusaldo =? where gads
> =?;",(result, [year]))
>
> Please bear in mind I am a noob in Python and I write spaggeti code.
>
> There is a table in my sqlite database called rezerve which shows the
> breakdown of a consolidated reserves item in a consolidated balance
> sheet report (if that says anything to you) by years. For the previous
> years the numbers does not change since they are already reported but
> for the current year it may change month by month until reported.
> Therefore, I wanted to update the numbers for the current year.
>
> The above python function works OK.
>
> Thanks
>
> Aivars
>
>
> 2008/12/2 Alan Gauld <alan.gauld@...>:
>>
>> "aivars" <aivars868@...> wrote
>>
>>> oCon.execute("UPDATE rezerve SET latusaldo =? where gads =?;",(result,
>>> [year]))
>>> oCon.commit()
>>>
>>> it throws me the error:
>>> sqlite3.InterfaceError: error binding parameter 1 probably unsupported
>>> type
>>
>> I assume its the [year] value it objects to.
>> I'm not sure what you expect SQLite to do with a list as a value, it does
>> not support a list type field.
>>
>>> All works OK when using INSERT with the same parameters.
>>
>> Are you sure? You can insert a list into a field?
>>
>>> Maybe I should as this question on sqlite list?
>>
>> Perhaps but I think it is the list parameter that it doesn't like.
>> Unless I misunderstand the syntax.
>>
>> --
>> Alan Gauld
>> Author of the Learn to Program web site
>> http://www.freenetpages.co.uk/hp/alan.gauld
>>
>> _______________________________________________
>> Tutor maillist - Tutor@...
>> http://mail.python.org/mailman/listinfo/tutor
>>
>

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[Fwd: Python Course]

2008-12-02T08:40:04Z

This was forwarded to me from one of our user group members:

"Hi everyone!

I just signed up for an online course in "Web Development with Python"
through DePaul University, which I think you might find interesting:
http://ipd.cdm.depaul.edu/wdp/Prog_WDP.htm

I talked to the folks in the admissions department and they said they
needed 10 students enrolled in order to go through with the course.
So I told them I would mention this to the python programmers I knew
to try to drum up enough applicants.

Best regards,

John T."

If anyone has any objection to posting this type of information, please
let me know. I thought members might be interested in available Python
courses.

--
Jeff

Jeff Johnson
jeff@...
Phoenix Python User Group - sunpiggies@...
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Re: noise function

2008-12-02T04:32:44Z

There's probably something like what you want within the "random" module.

at the interactive prompt, try:

import random
help(random)

---
Richard "Roadie Rich" Lovely, part of the JNP|UK Famile
www.theJNP.com

2008/12/2 Alan Gauld <alan.gauld@...>:

>
> "Christopher Spears" <cspears2002@...> wrote
>>
>> Does anyone know if python has a noise function?
>
> What kind of noise function?
> What would you expect it to produce?
> A stream of random numbers perhaps?
> A single number each time it is called?
>
> And which noise profile should it follow?
> Or would it be a multi dimensional noise model?
>
> I don't know of any such function and I'm not sure wiothout more details how
> it would work in a general way even if it did exist. Can you give a
> speciofic example of what you expect?
>
> --
> Alan Gauld
> Author of the Learn to Program web site
> http://www.freenetpages.co.uk/hp/alan.gauld
>
> _______________________________________________
> Tutor maillist - Tutor@...
> http://mail.python.org/mailman/listinfo/tutor
>

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Re: cgi on novell/Appache

2008-12-02T01:01:21Z

"Jim Morcombe" <jmorcombe@...> wrote

> running under Novel. I know absolutely nothing about novell. I
> need to have the first line of the script point to the Python
> interpretter,

I don't think that will do anything under Novell, assuming you mean
the Novell network OS and not Novell Linux? If its NovelWare then
you need to set the PATH to Python and set up the file associatiion
between your .py file and python. Then you need to use the cgi-bin
folder to store the file rather than your web app space.

At least that's what I did the last time I used a DOS based
server - but that was about 12 years ago!

If it's Novell Linux the standard /env/python should work.

> around on it. I have to change the script, give it to the admin guy
> and let him load it. He knows nothing about cgi, python, etc. )

HTH,

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: sqlite3 Python25 parameter binding problem with UPDATEplease help

2008-12-02T00:55:17Z

"aivars" <aivars868@...> wrote

> oCon.execute("UPDATE rezerve SET latusaldo =? where gads
> =?;",(result, [year]))
> oCon.commit()
>
> it throws me the error:
> sqlite3.InterfaceError: error binding parameter 1 probably
> unsupported type

I assume its the [year] value it objects to.
I'm not sure what you expect SQLite to do with a list as a value, it
does
not support a list type field.

> All works OK when using INSERT with the same parameters.

Are you sure? You can insert a list into a field?

> Maybe I should as this question on sqlite list?

Perhaps but I think it is the list parameter that it doesn't like.
Unless I misunderstand the syntax.

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: noise function

2008-12-02T00:51:10Z

"Christopher Spears" <cspears2002@...> wrote

> Does anyone know if python has a noise function?

What kind of noise function?
What would you expect it to produce?
A stream of random numbers perhaps?
A single number each time it is called?

And which noise profile should it follow?
Or would it be a multi dimensional noise model?

I don't know of any such function and I'm not sure wiothout
more details how it would work in a general way even if it
did exist. Can you give a speciofic example of what you expect?

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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cgi on novell/Appache

2008-12-02T00:39:15Z

I have a cgi script that I want to get running on an Apache server
running under Novel. I know absolutely nothing about novell. I need to
have the first line of the script point to the Python interpretter, but
have no idea where it is. (I don't have access to the server to play
around on it. I have to change the script, give it to the admin guy and
let him load it. He knows nothing about cgi, python, etc. )

What is the novel equivalent of "/usr/bin/python"?

Jim

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sqlite3 Python25 parameter binding problem with UPDATE please help

2008-12-01T23:12:54Z

Hello,

Does sqlite3 in python 2.5 supports parameter bindings in UPDATE
statement? When I do like the following:

oCon.execute("UPDATE rezerve SET latusaldo =? where gads =?;",(result, [year]))
oCon.commit()

it throws me the error:
sqlite3.InterfaceError: error binding parameter 1 probably unsupported type

All works OK when using INSERT with the same parameters.

On Google I found that python with MySQL supports this syntax (sorry I
am not able to find the link now) but I am not able to get it working
with sqlite3

Thanks in advance

Maybe I should as this question on sqlite list?

Aivars
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noise function

2008-12-01T21:43:41Z

Hi!

Does anyone know if python has a noise function?

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I asked about loops

2008-12-01T19:57:12Z

and your response was most gratifying. I think that I now have a handle
on the subject and want to say, "Thanks to you all." WM
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Re: attribute of built-in type

2008-12-01T19:03:40Z

Here is an idea that might help - you do have some control over
assignment to attributes of an object. If you stored your objects in
another object you could assign __name__ attributes automatically. For
example:

class Container(object):
def __setattr__(self, name, value):
if not hasattr(value, '__name__'):
try:
value.__name__ = name
except:
pass
object.__setattr__(self, name, value)

class Item(object):
pass

c = Container()
c.s = 'string'
c.i = Item()

print c.i.__name__ # i
print c.s.__name__ # AttributeError, can't add __name__ attribute to string

Kent
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Re: 'for' loops

2008-12-01T19:00:36Z

On Mon, Dec 1, 2008 at 7:56 PM, John Fouhy <john@...> wrote:

> [1] Technically, it iterates over an iterator, which you can think of
> as an object that behaves like a list when you throw it at a for loop.

The object of the 'in' must be an iterable, which is an object that
can produce an iterator when asked. A list is an iterable, not an
iterator.

Kent
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Re: try except block for multiple statements

2008-12-01T18:31:26Z

Bryan Fodness wrote:

> I would like to use a try except to see if a value exists. But, when
> I use the following, if a does not exist it exits. I understand why
> this does this, but is there a way to get b,c, and d if a does not
> exist without using a try except for every statement?
>
> try:
> fo.write("a = %s\n" %plan.a)
> fo.write("b = %s\n" %plan.b)
> fo.write("c = %s\n" %plan.c)
> fo.write("d = %s\n" %plan.d)
> except AttributeError:
> pass
>

def foo(obj, attr):
val = getattr(obj, attr, None)
if val is not None:
obj.write("%s = %s\n" % (attr, val))
foo(plan, "a")
foo(plan, "b")
foo(plan, "c")
foo(plan, "d")

> --
> "Any intelligent fool can make things bigger, more complex, and more
> violent. It takes a touch of genius - and a lot of courage - to move
> in the opposite direction. " -Albert Einstein
> ------------------------------------------------------------------------
>
> _______________________________________________
> Tutor maillist - Tutor@...
> http://mail.python.org/mailman/listinfo/tutor
>

--
Bob Gailer
Chapel Hill NC
919-636-4239

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Re: try except block for multiple statements

2008-12-01T17:54:26Z

On 02/12/2008, Bryan Fodness <bryan.fodness@...> wrote:

> I would like to use a try except to see if a value exists. But, when I use
> the following, if a does not exist it exits. I understand why this does
> this, but is there a way to get b,c, and d if a does not exist without using
> a try except for every statement?
>
> try:
> fo.write("a = %s\n" %plan.a)
> fo.write("b = %s\n" %plan.b)
> fo.write("c = %s\n" %plan.c)
> fo.write("d = %s\n" %plan.d)
> except AttributeError:
> pass

AFAIK, no -- but you could always use a loop.

attrs = ['a', 'b', 'c', 'd']
for attr in attrs:
try:
fo.write('A = %s\n' % getattr(plan, attr))
except AttributeError:
pass

--
John.
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Re: converting processing code to python code

2008-12-01T17:49:36Z

"Erica Osher" <eosher@...> wrote

>I wrote the original code in a program called Processing. (
> http://processing.org/)

Having had a look at the web site it is obvious that the hardest bit
of porting the Processing code to Python is that Python does not
support all the visual drawing functions that Processing does. Most
of them can be replicated by writing equivalent functions in Python
but that is a lot of work - effectively building a python vesion of
Processing! (That would be an exellent project BTW but not
one for a beginner!)

I tried a Google search. The best I could find was:

http://i.document.m05.de/?p=483

which suggests using Jython whicjh allows you to call the Java
processing libraies/classes from within Python code. But to
understand it I think you still need to go through the tutorials
first.

HTH,

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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try except block for multiple statements

2008-12-01T17:44:20Z

I would like to use a try except to see if a value exists. But, when I use the following, if a does not exist it exits. I understand why this does this, but is there a way to get b,c, and d if a does not exist without using a try except for every statement?

try:

    fo.write("a = %s\n" %plan.a)
    fo.write("b = %s\n" %plan.b)
    fo.write("c = %s\n" %plan.c)
    fo.write("d = %s\n" %plan.d)
except AttributeError:

pass

--
"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction. " -Albert Einstein

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Re: converting processing code to python code

2008-12-01T17:41:34Z

"Erica Osher" <eosher@...> wrote

>I wrote the original code in a program called Processing. (
> http://processing.org/)

Aha! The language is actually called Processing. Now that's
a new one on me. Thanks for the link, it does help to have
the context. :-)

Now the next question, are you experienced in Processing
or are you a beginner there too? If you are experienced in
another language the best tutiorial is the standard Python
tutorial found on the Python website. If you are a beginner
in Processing as well stick to the newbies tutors I mentioned
last time.

Regards,

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: converting processing code to python code

2008-12-01T17:28:10Z

I wrote the original code in a program called Processing. (http://processing.org/)

Thanks for your advice, I definitely need some tutorials.

On Mon, Dec 1, 2008 at 8:23 PM, Alan Gauld <alan.gauld@...> wrote:

"Erica Osher" <eosher@...> wrote

The code was originally created for a Processing Project and I'm just
starting to learn python and I'd like to build on this code.

The fact that you still don't tell us what the original language is suggests
you are not a very experienced programmer in any language. Is that
assumption correct?

The syntax error I get is

*Traceback (most recent call last):
File "nodebox/gui/mac/__init__.pyo", line 332, in _compileScript
File "<untitled>", line 8
int x1 = 5;
^
SyntaxError: invalid syntax

In Python variables are just names that refer to objects. The objects
can be of any type so we don't need to declare them as int, float,
char etc. You just need

x1 = 5

No semi colons are needed either.

However since this is such a basic Python statement I do think
you should take an hour or two to go through some of the complete
beginners tutorials found here:

http://wiki.python.org/moin/BeginnersGuide/NonProgrammers

Try mine if you like but there is a variety of styles for you to choose from.

Once you are familiar with the basics try converting your code again
and ask specific questions here for help. That will be much more
efficient for all of us than simply randomly trying things then asking
for help.

HTH,

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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--
Erica Osher

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Re: Tutor Digest, Vol 58, Issue 2

2008-12-01T17:27:08Z

"W W" <srilyk@...> wrote

>> for x in range(3):
>
> but the OP was looping from 3 to 1, and that's the easiest way I
> knew of.

Yes, but they weren't using the counter so it didn't matter which
way they looped. I suspect the decrement pattern was just the one
they were most familiar with in some other language (like Java? or
VB?)

Alan G

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Re: converting processing code to python code

2008-12-01T17:23:59Z

"Erica Osher" <eosher@...> wrote

> The code was originally created for a Processing Project and I'm
> just
> starting to learn python and I'd like to build on this code.

The fact that you still don't tell us what the original language is
suggests
you are not a very experienced programmer in any language. Is that
assumption correct?

> The syntax error I get is
>
> *Traceback (most recent call last):
> File "nodebox/gui/mac/__init__.pyo", line 332, in _compileScript
> File "<untitled>", line 8
> int x1 = 5;
> ^
> SyntaxError: invalid syntax

In Python variables are just names that refer to objects. The objects
can be of any type so we don't need to declare them as int, float,
char etc. You just need

x1 = 5

No semi colons are needed either.

However since this is such a basic Python statement I do think
you should take an hour or two to go through some of the complete
beginners tutorials found here:

http://wiki.python.org/moin/BeginnersGuide/NonProgrammers

Try mine if you like but there is a variety of styles for you to
choose from.

Once you are familiar with the basics try converting your code again
and ask specific questions here for help. That will be much more
efficient for all of us than simply randomly trying things then asking
for help.

HTH,

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: 'for' loops

2008-12-01T17:17:41Z

"WM." <wferguson1@...> wrote

>I recently asked a question about 'for' loops, expecting them to be
>similar to 'for-next' loops. I have looked at several on-line tutors
>but am still in the dark about what 'for' loops do.

Python for loops are like foreach loops in other languages.
A Python for loop executes a bit of code for each element
in a sequence (list, string, dictionary, set, file etc)
It will keep looping until it runs out of items in the
sequence.

Thus to print each letter in a string:

mystring = 'foobar'
for ch in mystring:
print ch

Or to print each element of a list:

mlist = [1,'2,'a',45, True]
for item in mylist:
print item

And if you want to loop for a fixed number of iterations simply
construct
a list with that number of elements. The range() function does that
for
us, thus:

for n in range(12):
print 'hi'

will print 'hi' 12 times.

> Does anyone have a plain English about the use of 'for' loops?
> Are 'while' loops the only way Python runs a sub-routine over &
> over?

while loops are used much less in Python than in other languages
because for loops are so powerful.
while lops are generally used in cases where you don't know how
many times you need to loop or you want to loop 'forever'.

while True:
print 'Can't stop me now!'

will keep on looping until you close the program

c = 0
while c != -1:
c = int(raw_input('Enter a number(-1 to stop) '))
print c

will keep looping until the user enters -1

More info and a comparison with JabaScript and VBScript can be
found in my tutor in the looping topic.

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: 'for' loops

2008-12-01T16:56:17Z

On 02/12/2008, WM. <wferguson1@...> wrote:
> I recently asked a question about 'for' loops, expecting them to be similar
> to 'for-next' loops. I have looked at several on-line tutors but am still
> in the dark about what 'for' loops do.
> Does anyone have a plain English about the use of 'for' loops?
> Are 'while' loops the only way Python runs a sub-routine over & over?

I'm not sure exactly what you understand by a "for-next loop".

A for loop, essentially, iterates over a list [1]. e.g.

for fruit in ['apple', 'pear', 'banana', 'tomato']:
print fruit

The loop will set the variable 'fruit' to be 'apple', 'pear', etc. on
each pass through the loop.

If you just want to do something n times, the usual idiom is:

for i in range(n):
# do something, possibly involving i

range(n) is a function that will produce the list [0, 1, 2, ..., n-1].

Tutorials should cover this, so I'm not sure if I'm telling you
anything new. If there's something particular you're stuck on, ask
:-)

--
John.

[1] Technically, it iterates over an iterator, which you can think of
as an object that behaves like a list when you throw it at a for loop.
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Re: 'for' loops

2008-12-01T16:53:28Z

On Mon, Dec 1, 2008 at 6:44 PM, WM. <wferguson1@...> wrote:

I recently asked a question about 'for' loops, expecting them to be similar to 'for-next' loops. I have looked at several on-line tutors but am still in the dark about what 'for' loops do.
Does anyone have a plain English about the use of 'for' loops?
Are 'while' loops the only way Python runs a sub-routine over & over?

For loops are mainly used when you want a specific number of iterations, such as looping over the elements of a list. In C/C++ you would do something like this:

int myarray[] = {1, 2, 3, 4, 5};
for(int x = 0; x < 5; x++)
printf("%d", myarray[x])

In python it would be much cleaner:

myarray = [1, 2, 3, 4, 5]
for x in myarray:
print x

HTH,
Wayne

--
To be considered stupid and to be told so is more painful than being called gluttonous, mendacious, violent, lascivious, lazy, cowardly: every weakness, every vice, has found its defenders, its rhetoric, its ennoblement and exaltation, but stupidity hasn't. - Primo Levi

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Re: 'for' loops

2008-12-01T16:52:05Z

On Mon, Dec 01, 2008 at 04:44:02PM -0800, WM. wrote:
> I recently asked a question about 'for' loops, expecting them to be
> similar to 'for-next' loops. I have looked at several on-line tutors but
> am still in the dark about what 'for' loops do.
> Does anyone have a plain English about the use of 'for' loops?
> Are 'while' loops the only way Python runs a sub-routine over & over?

No, both 'while' and 'for' loops are for running a block of code
(whether subroutine calls or whatever) over and over. The difference
between the two is that 'while' will continue repeating the block
for however many iterations it takes until the condition is satisfied
('while x is true, for some expression x'), a 'for' loop will run the
block of code a set number of times ('once for each element of some
set of values').

So if you want to execute 'print' for every line of a file, you
would do this:

for line in file:
print line

If you wanted to double a value until it exceeded 100, you would
use a while loop:

while x <= 100:
x *= 2

If you just want something executed a specific number of times,
(like print "hello" 10 times), you can use a for loop:

for i in range(10):
print "hello"

This is, just like any 'for' loop, executing the block once per
element of a list. The list in this case is range(10) which is
an expression that generates the list (0, 1, 2, ..., 9), so you
get one run through the code for each of those.

Does that help?

> _______________________________________________
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> http://mail.python.org/mailman/listinfo/tutor

--
Steve Willoughby | Using billion-dollar satellites
steve@... | to hunt for Tupperware.
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'for' loops

2008-12-01T16:44:02Z

I recently asked a question about 'for' loops, expecting them to be
similar to 'for-next' loops. I have looked at several on-line tutors but
am still in the dark about what 'for' loops do.
Does anyone have a plain English about the use of 'for' loops?
Are 'while' loops the only way Python runs a sub-routine over & over?
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Re: Tutor Digest, Vol 58, Issue 2

2008-12-01T16:23:31Z

On Mon, Dec 1, 2008 at 5:24 PM, Alan Gauld <alan.gauld@...> wrote:

<snip>Since the OP isn't using the loop counter a simpler solution
is simply

for x in range(3):

but the OP was looping from 3 to 1, and that's the easiest way I knew of.

-Wayne

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Re: converting processing code to python code

2008-12-01T15:45:25Z

On Mon, Dec 01, 2008 at 06:40:03PM -0500, Erica Osher wrote:
> The code was originally created for a Processing Project and I'm just
> starting to learn python and I'd like to build on this code.
>
> The syntax error I get is
>
> *Traceback (most recent call last):
> File "nodebox/gui/mac/__init__.pyo", line 332, in _compileScript
> File "<untitled>", line 8
> int x1 = 5;

That's not even close to Python syntax. That looks
like a C-derived language. I'd recommend going through
a basic Python tutorial first, so you can see how Python
works in a general sense before trying to convert code.

In Python, you don't need to declare variables like
that, you just assign them values. So that line would
be simply:

x1 = 5

> SyntaxError: invalid syntax
> *
> any suggestions?
>
> Thanks.
>
> On Mon, Dec 1, 2008 at 6:30 PM, Alan Gauld <alan.gauld@...>wrote:
>
> >
> > "Erica Osher" <eosher@...> wrote
> >
> > I have a simple processing code that I'm trying to work with in python,
> >> but
> >> I keep getting syntax errors. Any help on changing the code would be
> >> greatly
> >> appreciated. Thanks.
> >>
> >
> > It would help to have some background.
> > What language are you translating from? It could be C/C++/JavaScript or
> > Java.
> > Or possibly other C type languages. It might be significant!
> >
> > Also show us what you tried and the syntax error messages.
> > That way we can figure out what it is you are doing wrong.
> >
> > Otherwise we wind up writing your code for you and you learn nothing.
> > Then we have to do it all o er again next time you get stuck.
> > That's inefficient for both you and us!
> >
> >
> > --
> > Alan Gauld
> > Author of the Learn to Program web site
> > http://www.freenetpages.co.uk/hp/alan.gauld
> >
> > _______________________________________________
> > Tutor maillist - Tutor@...
> > http://mail.python.org/mailman/listinfo/tutor
> >
>
>
>
> --
> Erica Osher

> _______________________________________________
> Tutor maillist - Tutor@...
> http://mail.python.org/mailman/listinfo/tutor

--
Steve Willoughby | Using billion-dollar satellites
steve@... | to hunt for Tupperware.
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Re: converting processing code to python code

2008-12-01T15:40:03Z

The code was originally created for a Processing Project and I'm just starting to learn python and I'd like to build on this code.

The syntax error I get is

Traceback (most recent call last):
File "nodebox/gui/mac/__init__.pyo", line 332, in _compileScript
File "<untitled>", line 8
int x1 = 5;
^
SyntaxError: invalid syntax

any suggestions?

Thanks.

On Mon, Dec 1, 2008 at 6:30 PM, Alan Gauld <alan.gauld@...> wrote:

"Erica Osher" <eosher@...> wrote

I have a simple processing code that I'm trying to work with in python, but
I keep getting syntax errors. Any help on changing the code would be greatly
appreciated. Thanks.

It would help to have some background.
What language are you translating from? It could be C/C++/JavaScript or Java.
Or possibly other C type languages. It might be significant!

Also show us what you tried and the syntax error messages.
That way we can figure out what it is you are doing wrong.

Otherwise we wind up writing your code for you and you learn nothing.
Then we have to do it all o er again next time you get stuck.
That's inefficient for both you and us!

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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--
Erica Osher

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Re: converting processing code to python code

2008-12-01T15:30:20Z

"Erica Osher" <eosher@...> wrote

>I have a simple processing code that I'm trying to work with in
>python, but
> I keep getting syntax errors. Any help on changing the code would be
> greatly
> appreciated. Thanks.

It would help to have some background.
What language are you translating from? It could be C/C++/JavaScript
or Java.
Or possibly other C type languages. It might be significant!

Also show us what you tried and the syntax error messages.
That way we can figure out what it is you are doing wrong.

Otherwise we wind up writing your code for you and you learn nothing.
Then we have to do it all o er again next time you get stuck.
That's inefficient for both you and us!

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: Tutor Digest, Vol 58, Issue 2

2008-12-01T15:24:38Z

"W W" <srilyk@...> wrote

> for x in xrange(3, 0, -1):
> ....: print x
> ....:
> ....:
> 3
> 2
> 1

Since the OP isn't using the loop counter a simpler solution
is simply

for x in range(3):

>> i,j,k = 3,3,3
>> while i != 1:
>> print 'Larry, Moe & Curly Joe!'
>> i -= 1
>> while j != 1:
>> print 'Go Mad!!'
>> j -= 1
>> while k != 1:
>> print 'Go-go bad-bad!!'
>> k -= 1
>> print '\nBye-bye.'
>>
>> I am trying to learn loops. These nested 'whiles' work OK but I
>> would like
>> to wrap this script in a 'for' loop. I have not been able to make
>> that work.

To the OP:
It helps if you show us what you tried so that we can see where
the misunderstanding is. What did you do and what happened?

--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld

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Re: converting processing code to python code

2008-12-01T13:02:02Z

On Mon, Dec 01, 2008 at 12:59:23PM -0800, Steve Willoughby wrote:

> > void drawSquare1() {
> > if(x1<0 || x1>width-size) {
> > x1Speed = -x1Speed;
> > }
> >
> > if(y1<0 || y1>height-size) {
> > y1Speed = -y1Speed;
> > }
>
> def drawSquare1():
> if (x1 < 0 or x1 > width-size):
> x1 += x1Speed
> y1 += y1Speed
> rect(x1, y1, size, size)

I think my eyes skipped somewhere while copying that
over. The exact translation of that code snippet would
of course have been:

def drawSquare1():
if x1 < 0 or x1 > width-size:
x1Speed = -x1Speed
if y1 < 0 or y1 > height-size:
y1Speed = -y1Speed

Sorry 'bout that.

--
Steve Willoughby | Using billion-dollar satellites
steve@... | to hunt for Tupperware.
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Re: converting processing code to python code

2008-12-01T12:59:23Z

On Mon, Dec 01, 2008 at 03:48:59PM -0500, Erica Osher wrote:
> I have a simple processing code that I'm trying to work with in python, but
> I keep getting syntax errors. Any help on changing the code would be greatly
> appreciated. Thanks.

Could you show us what you have so far in Python and what syntax errors
you get?

Just as one example, this would be
pretty straightforward to convert straight
to Python, syntactically. Whether you'd
want to restructure the application to be
more optimally "Pythonic" is another topic
depending on what else is going on (or is
this the entire program)?

> void drawSquare1() {
> if(x1<0 || x1>width-size) {
> x1Speed = -x1Speed;
> }
>
> if(y1<0 || y1>height-size) {
> y1Speed = -y1Speed;
> }

def drawSquare1():
if (x1 < 0 or x1 > width-size):
x1 += x1Speed
y1 += y1Speed
rect(x1, y1, size, size)

Is that the sort of code you're coming up with?

One thing that strikes me off the top here is that
(in either language) you'd be better off not using
all those global variables. Make your functions take
parameters and use them in your calculations.

--
Steve Willoughby | Using billion-dollar satellites
steve@... | to hunt for Tupperware.
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converting processing code to python code

2008-12-01T12:48:59Z

I have a simple processing code that I'm trying to work with in python, but I keep getting syntax errors. Any help on changing the code would be greatly appreciated. Thanks.

void setup() {
size(550, 500);
noStroke();
smooth();
fill(255, 255, 255, 150);
}

//Square 1 vars
int x1 = 5;
int y1 = 10;

int x1Speed = 2;
int y1Speed = 2;

//Square 2 Vars
int x2 = 150;
int y2 = 100;

int x2Speed = 4;
int y2Speed = 4;

int size = 100;

void draw() {
background(180, 0, 0);
drawSquare1();
drawSquare2();

checkCollision();
}

void drawSquare1() {
if(x1<0 || x1>width-size) {
x1Speed = -x1Speed;
}

if(y1<0 || y1>height-size) {
y1Speed = -y1Speed;
}

x1+= x1Speed;
y1+= y1Speed;
rect(x1, y1, size, size);
}

void drawSquare2() {
if(x2<0 || x2>width-size) {
x2Speed = -x2Speed;
}

if(y2<0 || y2>height-size) {
y2Speed = -y2Speed;
}

x2+= x2Speed;
y2+= y2Speed;
rect(x2, y2, size, size);
}

void checkCollision() {
if(abs(x1-x2) < size && abs(y1-y2) < size) {
println("Collision");
//fill(255, 255, 255, 200);
x1Speed=-x1Speed;
x2Speed=-x2Speed;

y1Speed=-y1Speed;
y2Speed=-y2Speed;
} else {
fill(255, 255, 255, 100);
};
}

--
Erica Osher

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Re: Tutor Digest, Vol 58, Issue 2

2008-12-01T12:38:28Z

Try this:

for x in xrange(3, 0, -1):
   ....:     print x
   ....:
   ....:
3
2
1

HTH,
Wayne

On Mon, Dec 1, 2008 at 2:20 PM, WM. <wferguson1@...> wrote:

Stooges.py

i,j,k = 3,3,3
while i != 1:
print 'Larry, Moe & Curly Joe!'
i -= 1
while j != 1:
print 'Go Mad!!'
j -= 1
while k != 1:
print 'Go-go bad-bad!!'
k -= 1
print '\nBye-bye.'

I am trying to learn loops. These nested 'whiles' work OK but I would like to wrap this script in a 'for' loop. I have not been able to make that work.

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