不包括基于列和的dataframe的列。

I'm working on a data set that includes community data, and many of the columns (species) have a lot of zeroes. I would like to be able to drop these columns for some of the analyses I'm doing, based on the sum of the whole column. I'm tempted to do this with a for loop, but I hear that the apply and by functions are better when you're using R. My goal is to remove all columns with a sum of less than 15. I have used I'm working on a data set that includes communi