r - Change the class from numeric to factor of many columns in a data frame -

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what quickest/best way change large number of columns numeric factor?

i used following code appears have re-ordered data.

> head(stats[,1:2])   rk                 team 1  1 washington capitals* 2  2     san jose sharks* 3  3  chicago blackhawks* 4  4     phoenix coyotes* 5  5   new jersey devils* 6  6   vancouver canucks*  for(i in c(1,3:ncol(stats))) {     stats[,i] <- as.numeric(stats[,i]) }  > head(stats[,1:2])   rk                 team 1  2 washington capitals* 2 13     san jose sharks* 3 24  chicago blackhawks* 4 26     phoenix coyotes* 5 27   new jersey devils* 6 28   vancouver canucks*

what best way, short of naming every column in:

df$colname <- as.numeric(ds$colname)

further ramnath's answer, behaviour experiencing due as.numeric(x) returning internal, numeric representation of factor x @ r level. if want preserve numbers levels of factor (rather internal representation), need convert character via as.character() first per ramnath's example.

your for loop reasonable apply call , might more readable intention of code is. change line:

stats[,i] <- as.numeric(stats[,i])

to read

stats[,i] <- as.numeric(as.character(stats[,i]))

this faq 7.10 in r faq.

hth


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