Hi,
I have a data-frame,  r (column names below), that needs subsetting:
date, time, strain, gene, deltact

When I try to subset r by applying selection criteria on two columns I get
an empty data frame. For example I would like to extract all rows that have
time == 0h and strain == ROC.
So, t <- subset(r, (r$time == "0h" && r$strain == "ROC"), select= c(time,
strain, gene, deltact)) returns an empty data-frame.
Is it not possible to subset based on two criteria?
TIA
Anjan

-- 
===================================
anjan purkayastha, phd.
research associate
fas center for systems biology,
harvard university
52 oxford street
cambridge ma
phone-703.740.6939
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