that did the trick. thanks a lot! john
jim holtman wrote:
Actually change the TreeTag to characters first because you are trying to store in a new factor value that is not there yr1bp$TreeTag <- as.character(yr1bp$TreeTag)yr1bp$TreeTag[1501]<-sub("1.00", "1", yr1bp$TreeTag[1501]) # change back to a factor if desired yr1bp$TreeTag <- factor(yr1bp$TreeTag)On Sat, Jun 7, 2008 at 8:22 AM, jim holtman <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote:try:yr1bp$TreeTag[1501]<-sub("1.00", "1",as.character(yr1bp$TreeTag[1501]))Since it appears that TreeTag is a factor. This can be verifiedwith 'str'. On Fri, Jun 6, 2008 at 11:22 PM, john.polo <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote: Daniel Folkinshteyn wrote: works for me: > sub('1.00', '1', '1.00E-20') [1] "1E-20" when i input what you wrote, i get the same result. but that doesn't change the value for TreeTag at row 1501, it's just floating around in space. if i try it for yr1bp$TreeTag[1501], which is 1.00E-20 i get this: > yr1bp$TreeTag[1501]<-sub("1.00", "1", yr1bp$TreeTag[1501]) Warning message: In `[<-.factor`(`*tmp*`, 1501, value = "1E-20") : invalid factor level, NAs generated and then 1501 turns into: 1501 <NA> 2001 adult 32.5 which is less useful than the way it was originally input. thanks for the suggestion. john finally, if all your target strings are of the form 1.00E-20, you could sub the whole thing with a more general regexp: sub("([0-9])(\.[0-9]{2})(.*)", "\\1\\3", yourvector) (it matches a digit, followed by a dot and two digits, followed by "anything else", and takes out the "dot and two digits" bit in the replacement, in the whole vector.) thanks for that suggestion. it could come in handy. on 06/06/2008 03:25 PM john.polo said the following: dear R users, the data frame (read in from a csv) looks like this: TreeTag Census Stage DBH 1 CW-W740 2001 juvenile 5.8 2 CW-W739 2001 juvenile 4.3 3 CW-W738 2001 juvenile 4.7 4 CW-W737 2001 juvenile 5.4 5 CW-W736 2001 juvenile 7.4 6 CW-W735 2001 juvenile 5.4 ... 1501 1.00E-20 2001 adult 32.5 i would like to change values under the TreeTag column. as the last value shows, some of the tags have decimals followed by 2 decimal places. i just want whole numbers, i.e. not 1.00E-20, but 1E-20. i have a rough understanding of regexp and grepped all the positions that have the inappropriate tags. i tried sub() a couple of different ways, like yr1bp$TreeTag[1501]<-sub("1.00", "1", yr1bp$TreeTag[1501]) and after turning yr1bp$TreeTag[1501] into <NA>, yr1bp$TreeTag[1501]<-sub("", "1E-20", yr1pb$TreeTag[1501]) and sub("", "1E-20", yr1bp$TreeTag[1501]) but it's not working. i guess it has something to do with the data.frame characteristics i'm not aware of or don't understand. would i somehow have to tear apart the columns, edit them, and then put it back together? not that i know how to do that, but i'm wondering out loud. john
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