R help - Jun 2011 - modify a data frame by values in the columns

I have a data frame like this:

    col1 col2
r1     2    1
r2     4    3
r3     6    5
r4     8    7
r5    10    9
r6    12   11
r7    14   13
r8    16   15
r9    18   17
r10   20   19

I want to modify this data frame, for example, assign every row in column
col1 and col2 to -1 if the values in col1 is less than 12 and values in col2
is greater than 10. The result should look like this:
    col1 col2
r1     -1    1
r2     -1    3
r3     -1    5
r4     -1    7
r5     -1    9
r6    12   -1
r7    14   -1
r8    16   -1
r9    18   -1
r10  20   -1

I have been struggling to make it to work. Any help is appreciated!

Jason


--
View this message in context:
http://r.789695.n4.nabble.com/modify-a-data-frame-by-values-in-the-columns-tp3571995p3571995.html
Sent from the R help mailing list archive at Nabble.com.

Hi Jason,

This is one way;

c1 <- seq(2,20,2)
c2 <- seq(1,19,2)
c3 <- cbind(c1,c2)

c3[,1][which(c3[,1]<12)] <- -1
c3[,2][which(c3[,2]>10)] <- -1

Muhammad

On Fri, 3 Jun 2011, Jason024 wrote:
> I have a data frame like this:
>
>    col1 col2
> r1     2    1
> r2     4    3
> r3     6    5
> r4     8    7
> r5    10    9
> r6    12   11
> r7    14   13
> r8    16   15
> r9    18   17
> r10   20   19
>
> I want to modify this data frame, for example, assign every row in column
> col1 and col2 to -1 if the values in col1 is less than 12 and values in
col2
> is greater than 10. The result should look like this:
>    col1 col2
> r1     -1    1
> r2     -1    3
> r3     -1    5
> r4     -1    7
> r5     -1    9
> r6    12   -1
> r7    14   -1
> r8    16   -1
> r9    18   -1
> r10  20   -1
>
> I have been struggling to make it to work. Any help is appreciated!
>
> Jason
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/modify-a-data-frame-by-values-in-the-columns-tp3571995p3571995.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
>

On 2011-06-03 13:34, Jason024 wrote:
> I have a data frame like this:
>
>      col1 col2
> r1     2    1
> r2     4    3
> r3     6    5
> r4     8    7
> r5    10    9
> r6    12   11
> r7    14   13
> r8    16   15
> r9    18   17
> r10   20   19
>
> I want to modify this data frame, for example, assign every row in column
> col1 and col2 to -1 if the values in col1 is less than 12 and values in
col2
> is greater than 10. The result should look like this:
>      col1 col2
> r1     -1    1
> r2     -1    3
> r3     -1    5
> r4     -1    7
> r5     -1    9
> r6    12   -1
> r7    14   -1
> r8    16   -1
> r9    18   -1
> r10  20   -1
>
> I have been struggling to make it to work. Any help is appreciated!
This seems made for within(); calling your data.frame 'd':

  d.new <- within(d, {
                      col1 <- ifelse(col1 < 12, -1, col1)
                      col2 <- ifelse(col2 > 10, -1, col2)
                     })


Peter Ehlers
>
> Jason
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/modify-a-data-frame-by-values-in-the-columns-tp3571995p3571995.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.