On 2011-02-16 09:42, Sam Steingold wrote:
Description:
'lapply' returns a list of the same length as 'X', each element of
which is the result of applying 'FUN' to the corresponding element
of 'X'.
I expect that when I do
lapply(vec,f)
f would be called _once_ for each component of vec.
this is not what I see:
parse.num<- function (s) {
cat("parse.num1\n"); str(s)
s<- as.character(s)
cat("parse.num2\n"); str(s)
if (s == "N/A") return(s);
as.numeric(gsub("M$","e6",gsub("B$","e9",s)));
}
vec
mcap
1 200.5B
2 19.1M
3 223.7B
4 888.0M
5 141.7B
6 273.5M
7 55.649B
str(vec)
'data.frame': 7 obs. of 1 variable:
$ mcap: Factor w/ 7 levels "141.7B","19.1M",..: 3 2 4 7 1 5 6
vec<-lapply(vec,parse.num)
parse.num1
Factor w/ 7 levels "141.7B","19.1M",..: 3 2 4 7 1 5 6
parse.num2
chr [1:7] "200.5B" "19.1M" "223.7B" "888.0M" "141.7B" "273.5M" ...
Warning message:
In if (s == "N/A") return(s) :
the condition has length> 1 and only the first element will be used
i.e., somehow parse.num is called on the whole vector vec, not its
components.
what am I doing wrong?
Your 'vec' is NOT a vector. As your str(vec) clearly
shows, you have a *data.frame*. The components of a
data.frame are the columns (variables) of which you
have only one and your function is applied to that.
If you had two columns, parse.num would be applied
to each column.
So do this:
lapply(vec[, 1], parse.num)
Peter Ehlers
______________________________________________
[email protected] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
