Delete Block of Rows

[nmarti]

I am trying to delete a section of rows from a data frame (based on no condition).  Lets say my data frame has 200 rows and I want to delete rows 1 through 25.  How would I do this?

I know x[ -1, ] deletes the first row (or any desired row).  I tried using different variations of this, like x[ -c(1:25), ] but that didn't work.  I also tried writting a few functions, for example:

deleteRows <- function( data, s, e, ) {
for( i in s:e )
data[ -i, ]
}
deleteRows( ds, 1, 25 )

But that didn't work either, it only deleted row 25 (i'm new to writing functions).
Any thoughts on how to solve my problem would be appreciated.

[milton ruser]

Hi there,

I don´t know if you are trying to solve the delete job or to test how
functions work.

If you really want to delete lines from a data.frame, try something like
this.


rowcount<-1:100
x<-runif(100)
y<-runif(100)

df<-data.frame(cbind(rowcount,x,y))

df.subset<-subset(df, !(rownames(df) %in% 1:25))

     #    ! (a condition) is the negation of the condition

     #   so the output will be those lines that are not on interval 1:25



By the way, it is not a good idea to use "data" as a input argument on
a function because "data" is a pre-defined function.
Kind regards,

miltinho



On 6/15/08, nmarti <nate318i@...> wrote:

>
>
> I am trying to delete a section of rows from a data frame (based on no
> condition).  Lets say my data frame has 200 rows and I want to delete rows
> 1
> through 25.  How would I do this?
>
> I know x[ -1, ] deletes the first row (or any desired row).  I tried using
> different variations of this, like x[ -c(1:25), ] but that didn't work.  I
> also tried writting a few functions, for example:
>
> deleteRows <- function( data, s, e, ) {
> for( i in s:e )
> data[ -i, ]
> }
> deleteRows( ds, 1, 25 )
>
> But that didn't work either, it only deleted row 25 (i'm new to writing
> functions).
> Any thoughts on how to solve my problem would be appreciated.
> --
> View this message in context:
> http://www.nabble.com/Delete-Block-of-Rows-tp17849775p17849775.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@... mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

        [[alternative HTML version deleted]]


______________________________________________
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and provide commented, minimal, self-contained, reproducible code.

[Wacek Kusnierczyk]

nmarti wrote:
> I am trying to delete a section of rows from a data frame (based on no
> condition).  Lets say my data frame has 200 rows and I want to delete rows 1
> through 25.  How would I do this?
>
> I know x[ -1, ] deletes the first row (or any desired row).  I tried using
> different variations of this, like x[ -c(1:25), ] but that didn't work.  
what do you mean by 'didnt work'?
when you use negative indices, rows (or columns) from the input are
skipped in the output.  but to have a side effect of actually changing
the data frame, you need an assignment.  to modify your data frame, you
need:

x = x[-c(<your spec>),]

while x[-c(<your spec>),] will (should) return a df with rows skipped,
but x won't be changed.

> I
> also tried writting a few functions, for example:
>
> deleteRows <- function( data, s, e, ) {
> for( i in s:e )
> data[ -i, ]
> }
> deleteRows( ds, 1, 25 )
>
> But that didn't work either, it only deleted row 25

it didn't work, it didn't even delete row 25 from ds -- it *returned* a
df with all rows of ds except row 25 (in a bad style, i'd say).


> (i'm new to writing
> functions).
>  
consider reading the docs.

note that an implementation like

deleteRows = function(df, s, e) (df = df[-(s:e),,drop=FALSE])

won't work, because in r data frames are passed as arguments to
functions by value (you are welcome to argue that this is insane).

vQ

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[Moshe Olshansky-2]

I believe that x <- x[-(1:25),] should work.


--- On Sun, 15/6/08, nmarti <nate318i@...> wrote:

> From: nmarti <nate318i@...>
> Subject: [R]  Delete Block of Rows
> To: r-help@...
> Received: Sunday, 15 June, 2008, 11:02 PM
> I am trying to delete a section of rows from a data frame
> (based on no
> condition).  Lets say my data frame has 200 rows and I want
> to delete rows 1
> through 25.  How would I do this?
>
> I know x[ -1, ] deletes the first row (or any desired row).
>  I tried using
> different variations of this, like x[ -c(1:25), ] but that
> didn't work.  I
> also tried writting a few functions, for example:
>
> deleteRows <- function( data, s, e, ) {
> for( i in s:e )
> data[ -i, ]
> }
> deleteRows( ds, 1, 25 )
>
> But that didn't work either, it only deleted row 25
> (i'm new to writing
> functions).
> Any thoughts on how to solve my problem would be
> appreciated.
> --
> View this message in context:
> http://www.nabble.com/Delete-Block-of-Rows-tp17849775p17849775.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@... mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained,
> reproducible code.

______________________________________________
R-help@... mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[nmarti]

Thanks for all the replies.
My data frame is actually 4000 rows and 10 columns.

This line,
df <- subset( df, !( rownames(df) %in% 1:25 ) )  Did not work for me.  Is there a certain library I need to load for this to work (I'm assuming there isn't)?  I didn't get an error message, warning, or anything; it just didn't work.

These two lines did work,
df = df[ -c(1:25), ]    Or,
df = df[ 26:200, ]      I'm not sure why they didn't work the first time I tried them.

Once again, thanks for the help!

milton ruser wrote:

Hi there,

I don´t know if you are trying to solve the delete job or to test how
functions work.

If you really want to delete lines from a data.frame, try something like
this.


rowcount<-1:100
x<-runif(100)
y<-runif(100)

df<-data.frame(cbind(rowcount,x,y))

df.subset<-subset(df, !(rownames(df) %in% 1:25))

     #    ! (a condition) is the negation of the condition

     #   so the output will be those lines that are not on interval 1:25



By the way, it is not a good idea to use "data" as a input argument on
a function because "data" is a pre-defined function.
Kind regards,

miltinho



On 6/15/08, nmarti <[e-mail]> wrote:
>
>
> I am trying to delete a section of rows from a data frame (based on no
> condition).  Lets say my data frame has 200 rows and I want to delete rows
> 1
> through 25.  How would I do this?
>
> I know x[ -1, ] deletes the first row (or any desired row).  I tried using
> different variations of this, like x[ -c(1:25), ] but that didn't work.  I
> also tried writting a few functions, for example:
>
> deleteRows <- function( data, s, e, ) {
> for( i in s:e )
> data[ -i, ]
> }
> deleteRows( ds, 1, 25 )
>
> But that didn't work either, it only deleted row 25 (i'm new to writing
> functions).
> Any thoughts on how to solve my problem would be appreciated.
> --
> View this message in context:
> http://www.nabble.com/Delete-Block-of-Rows-tp17849775p17849775.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [e-mail] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

        [[alternative HTML version deleted]]


______________________________________________
[e-mail] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[milton ruser]

Hi there,

The subset function is available on your Base R. So you need not to load any
package.
May be it is not working because I suppose that your "rownames" is a
sequential one (1...4000). Case it is not true, the command will not work.

Anyway, I think that those line that are working find is simple than you use
%in%... etc.

Good luck,

miltinho
Brazil


On 6/16/08, nmarti <nate318i@...> wrote:

>
>
> Thanks for all the replies.
> My data frame is actually 4000 rows and 10 columns.
>
> This line,
> df <- subset( df, !( rownames(df) %in% 1:25 ) )  Did not work for me.  Is
> there a certain library I need to load for this to work (I'm assuming there
> isn't)?  I didn't get an error message, warning, or anything; it just
> didn't
> work.
>
> These two lines did work,
> df = df[ -c(1:25), ]    Or,
> df = df[ 26:200, ]      I'm not sure why they didn't work the first time I
> tried them.
>
> Once again, thanks for the help!
>
>
>
> milton ruser wrote:
> >
> > Hi there,
> >
> > I don´t know if you are trying to solve the delete job or to test how
> > functions work.
> >
> > If you really want to delete lines from a data.frame, try something like
> > this.
> >
> >
> > rowcount<-1:100
> > x<-runif(100)
> > y<-runif(100)
> >
> > df<-data.frame(cbind(rowcount,x,y))
> >
> > df.subset<-subset(df, !(rownames(df) %in% 1:25))
> >
> >      #    ! (a condition) is the negation of the condition
> >
> >      #   so the output will be those lines that are not on interval 1:25
> >
> >
> >
> > By the way, it is not a good idea to use "data" as a input argument on
> > a function because "data" is a pre-defined function.
> > Kind regards,
> >
> > miltinho
> >
> >
> >
> > On 6/15/08, nmarti <nate318i@...> wrote:
> >>
> >>
> >> I am trying to delete a section of rows from a data frame (based on no
> >> condition).  Lets say my data frame has 200 rows and I want to delete
> >> rows
> >> 1
> >> through 25.  How would I do this?
> >>
> >> I know x[ -1, ] deletes the first row (or any desired row).  I tried
> >> using
> >> different variations of this, like x[ -c(1:25), ] but that didn't work.
> >> I
> >> also tried writting a few functions, for example:
> >>
> >> deleteRows <- function( data, s, e, ) {
> >> for( i in s:e )
> >> data[ -i, ]
> >> }
> >> deleteRows( ds, 1, 25 )
> >>
> >> But that didn't work either, it only deleted row 25 (i'm new to writing
> >> functions).
> >> Any thoughts on how to solve my problem would be appreciated.
> >> --
> >> View this message in context:
> >> http://www.nabble.com/Delete-Block-of-Rows-tp17849775p17849775.html
> >> Sent from the R help mailing list archive at Nabble.com.
> >>
> >> ______________________________________________
> >> R-help@... mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >
> >       [[alternative HTML version deleted]]
> >
> >
> > ______________________________________________
> > R-help@... mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/Delete-Block-of-Rows-tp17849775p17865279.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@... mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

        [[alternative HTML version deleted]]


______________________________________________
R-help@... mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.