If I understand you correctly, your data column is not a character.
class(mydata[,"my_column"])

If it's numeric or a factor, this should work

# convert it to character to split apart the individual digits
# then convert the digits to numeric, and calculate the sum
sapply(strsplit(as.character(mydata[, "my_column"]), ""), function(x) 
sum(as.numeric(x)))

Jean


`·.,,  ><(((º>   `·.,,  ><(((º>   `·.,,  ><(((º>

Jean V. Adams
Statistician
U.S. Geological Survey
Great Lakes Science Center
223 East Steinfest Road
Antigo, WI 54409  USA
http://www.glsc.usgs.gov  (GLSC web site)


-----

Jay josip.2000 at gmail.com 
Wed Jun 15 11:09:25 CEST 2011

Hi,

I have a dataframe column from which I want to calculate the number of
1's in each entry. Some column values could, for example, be
"0001001000" and "11110000111".

To get the number of occurrences from a string I use this:
sum(unlist(strsplit(mydata[,"my_column"], "")) == "1")

However, as my data is not in string form.. How do I convert it? l
tried:
lapply(mydata[,"my_column"],toString)

but I do not seem to get it right (or at least I do not understand the
output format).

Also, are there other options? Can I easily calculate the occurrences
directly from the integers?

	[[alternative HTML version deleted]]

