search for: cona_6h

I have a data frame like this xx<-data.frame(cbind(Sample=c('Ctrl_6h','1+0_6h','1+200_6h','1+5k_6h','Ctrl_5K_6h','ConA_6h'), IFIT1=c(24,25,24.7,24.5,24.2,24.8))) grep('[[:digit:]]h',xx$Sample) yy<-xx$Sample strsplit(yy,"_") I have to extract the time information separated by '_' in the sample names, i tried grep and strsplit, it looks that i am not providing some i...