[R] R: Replace values according to conditions
Guazzetti Stefano
Stefano.Guazzetti at ausl.re.it
Wed Apr 9 11:04:51 CEST 2008
A short way (not necessairly the best way), using the coercion from
logical to numeric, could be:
(mydata<-as.data.frame(matrix(sample(1:9, 12, repl=T), ncol=4)))
-1*(mydata <=3) + (mydata >=6)
For the second question start here:
help(Logic, package="base")
Stefano
-----Messaggio originale-----
Da: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]Per conto di Suhaila Zainudin
Inviato: mercoledì 9 aprile 2008 9.32
A: r-help at r-project.org
Oggetto: [R] Replace values according to conditions
Greetings R-users,
I have the following data called mydata in a data.frame
Col1 Col2 Col3 Col4 Col5
1 2 4 6 7
8 8 7 3 5
4 4 5 6 7
I want to replace the data according to the following conditions
Condition 1 if data <= 3, replace with -1
Condition 2 if data >=6, replace with 1
Condition 3 if data = 4 or data =5, replace with 0
So the expected output for the example, would be
Col1 Col2 Col3 Col4 Col5
-1 -1 0 1 1
1 1 1 -1 0
0 0 1 1 1
I have thought of using replace with each conditions, for example I tried
the following
myrep <- replace(mydata, mydat <= 3, -1 ) #Condition 1
I would have to repeat the function replace for each of the conditions to
get the expected output.
My questions are:
1. I would like to know if there are better ways to achieve the expected
output?
2. What are the symbols for OR and AND in R?
Thanks for any feedback
--
Suhaila Zainudin
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