colnames() function

[Ayala Allon]

Hi,

I wanted to ask if there is a way to use the colnmaes() function by providing the name of the column I want? and not by providing the index of the column?

For example I have

 z<- data.frame(x=1:10,y=11:20)

> z

    x  y

1   1 11

2   2 12

3   3 13

4   4 14

5   5 15

6   6 16

7   7 17

8   8 18

9   9 19

10 10 20

If I want to replace the name of the first column I'll do:

> colnames(z)[1]<-"new.name"

> z

   new.name  y

1         1 11

2         2 12

3         3 13

4         4 14

5         5 15

6         6 16

7         7 17

8         8 18

9         9 19

10       10 20

But how can I replace the name if I don't know (or don't want to find out) the index of the column for which I want to set the new name? 

For example if I want now to replace the name "new.name" to "xxx" by providing the name of the column (i.e., "new.name") and by providing the its index (i.e., z[1]). I tried for example 

colnames(z)[["new.name"]]<- "xxx"

but I get an error.

Any ideas? I have an idea how to pass it but I was wondering if there is a way to do it using colnames()

Thanks

Ayala

[Jonathan Rosenblatt]

One possibility:

names(z)[names(z) %in% 'x'] <- 'q'

Ayala

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[amit gal]

or use match()

[דוד ארנבורג‎]

Or 

colnames(z)[grepl("new.name", colnames(z))] <- "xxx"

[Jonathan Rosenblatt]

indeed

grepl also has the advantage of taking regular expressions.

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[Ayala Allon]

Thank you all for the suggestions!

Best

Ayala

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