[R] modify a data frame by values in the columns

[Peter Ehlers]

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
>
>
> --
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>
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