Daniel,
I think you might benefit from (re)reading the Intro to R materials, since you
seem to misunderstand both ifelse() and possibly how subsetting works.
I can't provide an actual example since I have no idea what sample or var
or sm are (and it's a VERY good idea to not use names for variables that
are already the names of functions).
But here are two possible ways to change "w" values to NA. Note that they
have different effects on the column class in a dataframe.
> mydata
V1 V2 V3 V4 V5 V6 V7
1 1 2 3 4 5 6 7
2 3 3 4 4 w w 1
3 w 3 6 5 7 8 9
4 4 4 w 5 3 3 0
> str(mydata)
'data.frame': 4 obs. of 7 variables:
$ V1: chr "1" "3" "w" "4"
$ V2: int 2 3 3 4
$ V3: chr "3" "4" "6" "w"
$ V4: int 4 4 5 5
$ V5: chr "5" "w" "7" "3"
$ V6: chr "6" "w" "8" "3"
$ V7: int 7 1 9 0
> # using ifelse()
> mydata1 <- ifelse(mydata != "w", NA, "w")
> mydata1
V1 V2 V3 V4 V5 V6 V7
[1,] NA NA NA NA NA NA NA
[2,] NA NA NA NA "w" "w" NA
[3,] "w" NA NA NA NA NA NA
[4,] NA NA "w" NA NA NA NA
> str(mydata1)
chr [1:4, 1:7] NA NA "w" NA NA NA NA NA NA NA NA ...
- attr(*, "dimnames")=List of 2
..$ : NULL
..$ : chr [1:7] "V1" "V2" "V3" "V4" ...
> # using direct subsetting
> mydata[mydata != "w"] <- NA
> mydata
V1 V2 V3 V4 V5 V6 V7
1 <NA> NA <NA> NA <NA> <NA> NA
2 <NA> NA <NA> NA w w NA
3 w NA <NA> NA <NA> <NA> NA
4 <NA> NA w NA <NA> <NA> NA
> str(mydata)
'data.frame': 4 obs. of 7 variables:
$ V1: chr NA NA "w" NA
$ V2: int NA NA NA NA
$ V3: chr NA NA NA "w"
$ V4: int NA NA NA NA
$ V5: chr NA "w" NA NA
$ V6: chr NA "w" NA NA
$ V7: int NA NA NA NA
On Sun, Feb 13, 2011 at 8:39 AM, Daniel M. <danielmes...@yahoo.com> wrote:
> Hello,
>
> I have some data file, say, mydata
>
> 1,2,3,4,5,6,7
> 3,3,4,4,w,w,1
> w,3,6,5,7,8,9
> 4,4,w,5,3,3,0
>
> i want to replace some percentages of "mydata" file in to NAs for those values
> that are NOT w's. I know how to apply the percentage thing here but don't know
> how to select those values that are not "w"s. So far, i was able to do it but
> the result replaces the w's also which i do not want to.
>
> Here is my code that i tried to exclude those w's(within my short codes)
>
> ifelse(mydata[sample,var] != 'w',mydata[sm,var]<-NA,'w')
> Can any one help please?
>
> Thank you
>
> Daniel
>
>
--
Sarah Goslee
http://www.functionaldiversity.org
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