On 12-Jan-10 17:46:47, karena wrote:
> hi, I have a question about importing data in R.
>
> I want to import a file which has missing value in it, and the missing
> values are denoted as ".", I want to first read in the file, and then
> change the "." into the number zero "0".
>
> how can I do that?
>
> thank you,
>
> karena
It may depend on what format the file is in, but if it is a tabular
text file or a CSV file then you can use the "na.strings" parameter.
Here is an example of a little CSV file with "." used for "missing":
file temp.csv:
--------------
A,B,C,D
1.1,1.2,1.3,1.4
2.1,2.2,.,2.4
3.1,.,3.3,3.4
4.1,.,.,4.4
D <- read.csv("temp.csv",na.strings=".")
D
# A B C D
# 1 1.1 1.2 1.3 1.4
# 2 2.1 2.2 NA 2.4
# 3 3.1 NA 3.3 3.4
# 4 4.1 NA NA 4.4
So the "." have gone in as NA (the right thing to do in the first
instance with missing data). Now you can replace these by zeros:
D[is.na(D)] <- 0
D
# 1 1.1 1.2 1.3 1.4
# 2 2.1 2.2 0.0 2.4
# 3 3.1 0.0 3.3 3.4
# 4 4.1 0.0 0.0 4.4
Ted.
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E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk>
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Date: 12-Jan-10 Time: 18:42:40
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