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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