[R] Finding the position of a variable in a data.frame
John Kane
jrkrideau at yahoo.ca
Wed Aug 2 23:01:53 CEST 2006
Simple problem but I don't see the answer. I'm trying
to clean up some data
I have 120 columns in a data.frame. I have one value
in a column named "blaw" that I want to change. How do
I find the coordinates. I can find the row by doing a
subset on the data.frame but how do I find out here
"blaw " is in columns without manually counting them
or converting names(Df) to a list and reading down the
list.
Simple example
cat <- c( 3,5,6,8,0)
dog <- c(3,5,3,6, 0)
rat <- c (5, 5, 4, 9, 0)
bat <- c( 12, 42, 45, 32, 54)
Df <- data.frame(cbind(cat, dog, rat, bat))
Df
subset(Df, bat >= 50)
----results
cat dog rat bat
5 0 0 0 54
Thus I know that my target is in row 5 but how do I
figure out where 'bat' is?
All I want to do is be able to say
Df[5,4] <- 100
Is there some way to have function(bat) return the
column number: some kind of a colnum() function? I
had thought that I had found somthing in
library(gdata) matchcols but no luck.
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