using $ for subsetting in R

Asked Jul 20 '17 at 13:01

Active Jul 20 '17 at 13:09

Viewed 58 times

I'm trying to change a column name by a variable using $

yy is a data frame

yy$AL$'heart attack' is a vector subset of yy:

> yy$AL$`heart attack`
 [1] 14.3 18.5 18.1   NA   NA   NA 17.7 18.0 15.9   NA 19.6 17.3   NA 17.8 17.5 15.4   NA 16.3   NA
[20] 15.0 17.1 17.1   NA 16.4 15.2 16.7   NA   NA 16.7 16.9 14.5 16.6   NA   NA   NA 15.8 15.2 16.2
[39]   NA 15.6 15.0   NA 17.1   NA   NA 16.7 15.6 15.0 15.8 16.8   NA   NA 17.0 15.2   NA 15.8   NA
[58]   NA 15.7 14.7 17.3   NA 14.9 16.8 14.6   NA   NA   NA 19.3 15.3 14.7   NA   NA   NA   NA   NA
[77]   NA 13.3   NA   NA 16.5 16.0   NA   NA 14.2 16.1   NA   NA   NA   NA 15.2   NA   NA   NA   NA
[96]   NA   NA   NA

having:

a <- "AL"
b <- "heart attack"

now yy$a$b doesn't work :

> a
[1] "AL"
> b
[1] "heart attack"
> yy$a$b
NULL

a & b are characters, is there another class so that yy$a$b works ?

edited Jul 20 '17 at 13:09

Steve

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asked Jul 20 '17 at 13:01

Yousri Hajri

2

`yy[a][b]`, maybe reading `?"$"` could help also. – Tensibai Jul 20 '17 at 13:20
1

For the sake of quoting it in case you miss it: "Both [[ and $ select a single element of the list. The main difference is that **$ does not allow computed indices, whereas [[ does** . x$name is equivalent to x[["name", exact = FALSE]]." – Tensibai Jul 20 '17 at 13:22
I understand, yy[[a]][[b]] works Many thanks – Yousri Hajri Jul 20 '17 at 13:56
Did you try it ? – Tensibai Jul 20 '17 at 13:57
Yes thanks a lot Steve – Yousri Hajri Jul 20 '17 at 13:58
You have list of list, not a data.frame... – Tensibai Jul 20 '17 at 14:01

using $ for subsetting in R

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