On Aug 28, 2010, at 1:24 PM, Laetitia Schmid wrote:
Hi,
Can anybody show me how to extract all columns in my dataset that
are polymorphic? Or phrased in another way I would like to delete
all columns that have no more than one letter in it (that are
monomorphic).
Assuming you read this in with read.table:
> table(sapply(txt.in, function(x) length(levels(x))))
0 1 2 3 4
18 112 31 10 1
I am further assuming you do not want the 18 columns with no levels
(presumably numeric or logical, ooops .... only ones with all "T"'s,
and got converted to logical, so no matter ) then:
> names(txt.in)[ sapply(txt.in, function(x) length(levels(x))) >1]
[1] "V1" "V2" "V5" "V23" "V27" "V29" "V30" "V34" "V45"
"V47" "V48" "V49"
[13] "V50" "V53" "V56" "V62" "V63" "V64" "V66" "V67" "V71"
"V73" "V81" "V90"
[25] "V95" "V104" "V107" "V109" "V114" "V116" "V121" "V124" "V126"
"V131" "V133" "V139"
[37] "V156" "V158" "V163" "V166" "V168" "V172"
so:
newdata <- txt.in[ , <the above expression here> ]
--
David Winsemius, MD
West Hartford, CT
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