[R] Convert list to data frame while controlling column types

[Alexander Shenkin]

On 8/21/2009 3:04 PM, David Winsemius wrote:
> 
> On Aug 21, 2009, at 3:41 PM, Alexander Shenkin wrote:
> 
>> Thanks everyone for their replies, both on- and off-list.  I should
>> clarify, since I left out some important information.  My original
>> dataframe has some numeric columns, which get changed to character by
>> gsub when I replace spaces with NAs.
> 
> If you used is.na() <-  that would not happen to a true _numeric_ vector
> (but, of course, a numeric vector in a data.frame could not have spaces,
> so you are probably not using precise terminology).

I do have true numeric columns, but I loop through my entire dataframe
looking for blanks and spaces for convenience.

> You would be well
> advised to include the actual code rather than applying loose
> terminology subject you your and our misinterpretation.

I did include code in my previous email.  Perhaps you were looking for
different parts.

> 
> ?is.na
> 
> 
> I am guessing that you were using read.table() on the original data, in
> which case you should look at the colClasses parameter.
> 

yep - I use read.csv, and I do use colClasses.  But as I mentioned
earlier, gsub converts those columns to characters.  Thanks for the tip
about is.na() <-.  I'm now using the following, thus side-stepping the
whole "controlling as.data.frame's column conversion" issue:

final_dataf = lapply(final_dataf, function(x){ is.na(x) <-
+ grep('^\\s*$',x); return(x) })