Autofill for variables not working

See the FAQ: How to do a minimal reproducible example reprex for beginners for more specific guidance.

In general:

  1. Favor shorter, lower-case variable names for programming.
  2. When it comes time to output for presentation is when it makes sense to change over to longer, more highly formatted and descriptive names.

If the desired variable names follow no particular pattern, an effective way to change them is simply with colnames.

colnames(mtcars)
#>  [1] "mpg"  "cyl"  "disp" "hp"   "drat" "wt"   "qsec" "vs"   "am"   "gear"
#> [11] "carb"
headers <- c("age","class","weight","iq","lipids","sugars","nacl","gender","grade","category","range")
colnames(mtcars) <- headers
head(mtcars)
#>                    age class weight  iq lipids sugars  nacl gender grade
#> Mazda RX4         21.0     6    160 110   3.90  2.620 16.46      0     1
#> Mazda RX4 Wag     21.0     6    160 110   3.90  2.875 17.02      0     1
#> Datsun 710        22.8     4    108  93   3.85  2.320 18.61      1     1
#> Hornet 4 Drive    21.4     6    258 110   3.08  3.215 19.44      1     0
#> Hornet Sportabout 18.7     8    360 175   3.15  3.440 17.02      0     0
#> Valiant           18.1     6    225 105   2.76  3.460 20.22      1     0
#>                   category range
#> Mazda RX4                4     4
#> Mazda RX4 Wag            4     4
#> Datsun 710               4     1
#> Hornet 4 Drive           3     1
#> Hornet Sportabout        3     2
#> Valiant                  3     1

If some transformation by function application of the colnames is desired, such as turning upper case to lower case, dplyr::rename can be used as shown in the help for rename

If the new names represent a regular sequence, a function to generate them can be used to create the header in the snippet above. For example, V_1 \dots V_n

colnames(mtcars) <- rep(paste0("V",1:11))
head(mtcars)
#>                     V1 V2  V3  V4   V5    V6    V7 V8 V9 V10 V11
#> Mazda RX4         21.0  6 160 110 3.90 2.620 16.46  0  1   4   4
#> Mazda RX4 Wag     21.0  6 160 110 3.90 2.875 17.02  0  1   4   4
#> Datsun 710        22.8  4 108  93 3.85 2.320 18.61  1  1   4   1
#> Hornet 4 Drive    21.4  6 258 110 3.08 3.215 19.44  1  0   3   1
#> Hornet Sportabout 18.7  8 360 175 3.15 3.440 17.02  0  0   3   2
#> Valiant           18.1  6 225 105 2.76 3.460 20.22  1  0   3   1

Note that

colnames(mtcars) <- header

modifies mtcars in place.