I am trying to create levels and colours for some graphs. However I get the Error – in seq.default “to” must be a finite number. Any help will be very much appreciated

wch <- as.numeric(substring(levels(DataSet$Header), 2,2))
colwch <- c(seq(1,table(wch)[1]),seq(1,table(wch)[2]),seq(1,table(wch)[3]),seq(1,table(wch)[4]))
Error in seq.default(1, table(wch)[1]) : ‘to’ must be a finite number