[R] how to use a column name from the data frame in the function

for example I have data frame m as below: m=as.data.frame(outer(1:5,6:9)) colnames(m)=c('a','b','c','d') and I define the function myf=function(df, colname){ suppose colname is a, then: how can I get the column 'a' and how to get the colname as a string, 'a' } Thank you!

[R] how to use a column name from the data frame in the function

m=as.data.frame(outer(1:5,6:9)) colnames(m)=c('a','b','c','d') tf=function(df, col){list(mean(eval(substitute(col),df,parent.frame())),col )} tf(m,a) will issue error: Error in tf(m, a) : object 'a' not found How can I replace the col as char 'a' in the function? Thank you

Re: [R] how to use a column name from the data frame in the function

Please don't post in HTML format... it messes with code examples. Use character indexing (please read the Introduction to R... again if necessary). myf - function(df, colname){ df[ ,colname ] } colname - a myf(m,colname) Until you learn simple R syntax, I strongly recommend avoiding