On May 31, 2010, at 5:29 PM, Mr. Natural wrote:
The data frame is lwf that records the survival of bushes over an 8
year
period. Years are called bouts. Dead bushes are recorded as zeros,
and live
bushes as "1."
str(lwf)
'data.frame': 638 obs. of 9 variables:
$ bushno: int 1 2 3 4 5 6 7 8 9 10 ...
$ bout1 : int 0 1 0 1 1 1 0 1 0 1 ...
$ bout2 : int 0 1 0 0 0 0 0 0 0 1 ...
$ bout3 : int 0 1 0 0 0 0 0 0 0 1 ...
$ bout4 : int 0 1 0 0 0 0 0 0 0 0 ...
$ bout5 : int 0 1 0 0 0 0 0 0 0 0 ...
$ bout6 : int 0 1 0 0 0 0 0 0 0 0 ...
$ bout7 : int 0 1 0 0 0 0 0 0 0 0 ...
$ bout8 : int 0 1 0 0 0 0 0 0 0 0 ...
head(lwf)
bushno bout1 bout2 bout3 bout4 bout5 bout6 bout7 bout8
1 1 0 0 0 0 0 0 0 0
2 2 1 1 1 1 1 1 1 1
3 3 0 0 0 0 0 0 0 0
4 4 1 0 0 0 0 0 0 0
5 5 1 0 0 0 0 0 0 0
6 6 1 0 0 0 0 0 0 0
A number of the data are incorrect. For example, that for bush 145
in year
three is recorded as dead="0"
when it should be alive ="1." The bushes do not come back to life
after
they die.
lwf[lw$bushno==145,]
bushno bout1 bout2 bout3 bout4 bout5 bout6 bout7 bout8
144 145 1 1 0 1 1 1 1 1
I know that I can do this with fix(lwf) or edit(lwf). However, I
would like
to learn some more R.
What code could I use to correct these data?
rle is a function that records lengths of runs and values. Your
problem is to find rows where the length of the rle encoded data is
more than two. Perhaps something like:
apply(lwf[ , -1], 1, function(x){ length( rle(x)$values ) >2 } )
I have been screwing around with such as
lwfb[(lwf$bushno==145) & (lwf$bout3==0),0]<- lwf[(lwf$bushno==145) &
(lwf$bout3==0),1]
to no avail.
If all you want to do is correct these by hand then:
lwf[lwf$bushno==145 , "bout3"] <- 1
Or if you want to work on a copy (safer):
lwfb <- lwf
lwfb[lwfb$bushno==145 , "bout3"] <- 1
Any help appreciated.Thanks, MN
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David Winsemius, MD
West Hartford, CT
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