Hi Hu
The problem you are having is related to the fact that the vectors
data$V4 and data$V5 are of class factor. This means they are numeric
(215, 134, etc), with an additional 'levels' attribute that links
those numbers to the character identifiers "P05761" etc:
# V4 is a numeric vector
sorry, pressed "sent" by mistake.
for example
>data <- read.csv("data.txt")
>data
V1 V2
1 YHR165C CG8877
2 YJL130C CG18572
3 YDL171C CG9674
4 YKR054C CG7507
5 YDL140C CG1554
6 YLR106C CG13185
7 YGL206C CG9012
8 YNL262W CG6768
9 YER
