separate genes with expression values I have a file like this with 2 columns. I want to separate the columns based on plus and minus signs into separate files. How do I do this with awk or sed. Kindly help.
What do you want to do with NA values?

The below scripts ignore them (h3ab74's answer will print them to positiveExpression)

awk '$2 ~ /^[0-9]+$/  {print $0}' expressionFile.txt &gt; positiveExpression.txt
awk '$2 ~ /^-[0-9]+$/ {print $0}' expressionFile.txt &gt; negativeExpression.txt


These do a regex match to respectively, positive and negative numbers. If there's anything else in field 2 the line won't be printed.