[R] Finding the position of a variable in a data.frame

From: John Kane <jrkrideau_at_yahoo.ca>
Date: Thu 03 Aug 2006 - 07:01:53 EST


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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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu Aug 03 07:18:27 2006

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