see below
Steven Yen wrote/hat geschrieben on/am 05.01.2021 08:14:
I constantly define variable lists from a data frame (e.g., to define a
regression equation). Line 3 below does just that. Placing each variable
name in quotation marks is too much work especially for a long list so I
do that with line 4. Is there an easier way to accomplish this----to
define a list of variable names containing "a","c","e"? Thank you!
data<-as.data.frame(matrix(1:30,nrow=6))
colnames(data)<-c("a","b","c","d","e"); data
a b c d e
1 1 7 13 19 25
2 2 8 14 20 26
3 3 9 15 21 27
4 4 10 16 22 28
5 5 11 17 23 29
6 6 12 18 24 30
x1<-c("a","c","e"); x1 # line 3
[1] "a" "c" "e"
x2<-colnames(subset(data,select=c(a,c,e))); x2 # line 4
[1] "a" "c" "e"
What about:
x3 <- names(data)[c(1,3,5)]
x3
[1] "a" "c" "e"
If I have to compile longer vectors of variable names I do it as follows:
First I use:
dput(names(data))
resulting in a vector of names.
c("a", "b", "c", "d", "e")
Then I edit the output by hand, e.g.
x4 <- c("a", "b", "c", "d", "e")
x4 <- c("a", "c", "e")
This is especially useful with long names, where I could easily make
typing errors.
regards,
Heinz
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