[R] selection of missing data

Hi i'm a french medical student, i have some data that i import from excel. My colomn of the datafram are the localisations of metastasis. If there is a metatsasis there is the symbol _. i want to exclude the row without metastasis wich represent the NA data. so, i wrote this mela is the data

Re: [R] selection of missing data

I do not quite follow your post but here are some suggestions. 1) You can the na.strings argument to simplify things df - read.delim(file=lala.txt, na.strings=- ) 2) If you can count the number of metastasis per row first, then find the rows with zero sum. met.cols -