How to include position number in str() output? - r

Question

I was wondering whether anybody has a neat solution for including position numbers of variables when getting str output.
Example:
Instead of getting this:
str(cars)
'data.frame': 50 obs. of 2 variables:
$ speed: num 4 4 7 7 8 9 10 10 10 11 ...
$ dist : num 2 10 4 22 16 10 18 26 34 17 ...
I would like to get something like this:
str(cars)
'data.frame': 50 obs. of 2 variables:
1 speed: num 4 4 7 7 8 9 10 10 10 11 ...
2 dist : num 2 10 4 22 16 10 18 26 34 17 ...
in order to be able to index data.frames more easily.

Answer 1

Here's a hastily modified version of glimpse from dplyr which does what you need:
library(dplyr)
glimpse_n <- function(tbl, width = getOption("width")) {
cat("Observations: ", nrow(tbl), "\n", sep = "")
if (ncol(tbl) == 0)
return(invisible())
cat("Variables:\n")
rows <- as.integer(width/3)
df <- as.data.frame(head(tbl, rows))
var_types <- vapply(df, type_sum, character(1))
var_names <- paste0(sprintf("%3d ", 1:length(names(df))), format(names(df)), " (", var_types,
") ")
data_width <- width - nchar(var_names) - 2
length_est <- pmin(ceiling(max(data_width)/3) + 1, nrow(tbl))
formatted <- vapply(df, function(x) paste0(dplyr:::format_v(x), collapse = ", "),
character(1), USE.NAMES = FALSE)
truncated <- dplyr:::str_trunc(formatted, data_width)
cat(paste0(var_names, truncated, collapse = "\n"), "\n",
sep = "")
}
glimpse_n(mtcars)
## Observations: 32
## Variables:
## 1 mpg (dbl) 21.0, 21.0, 22.8, 21.4, 18.7, 18.1, 14.3, 24.4, 22.8, 19.2, 17.8, 1...
## 2 cyl (dbl) 6, 6, 4, 6, 8, 6, 8, 4, 4, 6, 6, 8, 8, 8, 8, 8, 8, 4, 4, 4, 4, 8, 8...
## 3 disp (dbl) 160.0, 160.0, 108.0, 258.0, 360.0, 225.0, 360.0, 146.7, 140.8, 167....
## 4 hp (dbl) 110, 110, 93, 110, 175, 105, 245, 62, 95, 123, 123, 180, 180, 180, ...
## 5 drat (dbl) 3.90, 3.90, 3.85, 3.08, 3.15, 2.76, 3.21, 3.69, 3.92, 3.92, 3.92, 3...
## 6 wt (dbl) 2.620, 2.875, 2.320, 3.215, 3.440, 3.460, 3.570, 3.190, 3.150, 3.44...
## 7 qsec (dbl) 16.46, 17.02, 18.61, 19.44, 17.02, 20.22, 15.84, 20.00, 22.90, 18.3...
## 8 vs (dbl) 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0...
## 9 am (fctr) 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, ...
## 10 gear (dbl) 4, 4, 4, 3, 3, 3, 3, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 4, 4, 4, 3, 3, 3...
## 11 carb (dbl) 4, 4, 1, 1, 2, 1, 4, 2, 2, 4, 4, 3, 3, 3, 4, 4, 4, 1, 2, 1, 1, 2, 2...