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 <jholtman@gmail.com> 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 verified with
> 'str'.
>
>
>   On Fri, Jun 6, 2008 at 11:22 PM, john.polo <jpolo@mail.usf.edu> 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
>>>>
>>>> ______________________________________________
>>>> R-help@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<http://www.r-project.org/posting-guide.html>
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>>
>> ______________________________________________
>> R-help@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<http://www.r-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?




-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

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