sequential column names add 0

Question

I have a dataset with column names

 Col_a_b1   Col_a_b2   Col_a_b3  Col_a_b4   Col_a_b5   Col_a_b6   Col_a_b7   Col_a_b8   Col_a_b9  Col_a_b10   Col_a_b11 ...  Col_a_b94

How do I add 0s to column names 1 to 10 , expected column names

 Col_a_b01   Col_a_b02   Col_a_b03  Col_a_b04   Col_a_b05   Col_a_b06   Col_a_b07   Col_a_b08   Col_a_b09  Col_a_b10   Col_a_b11 ...  Col_a_b94

Any suggestions much appreciated. Thanks.

Nad Pat · Answer 1 · 2022-03-25T13:01:38.573

0

One way to do is

    #column names 
    nam = c( 'Col_a_b1',   'Col_a_b2' ,  'Col_a_b3')
    #extract the number
    num = parse_number(nam)
    #convert to two digits.  
    num = sub('(^[0-9]$)','0\\1', num)
    #remove the numbers
    nam = gsub('[0-9]+', '', nam)
    #add 0
    mod_nam = paste0(nam, num)
    [1] "Col_a_b01" "Col_a_b02" "Col_a_b03"

edited Mar 25 '22 at 13:01

answered Mar 25 '22 at 05:32

Nad Pat

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For a colname `"Col_a_b94"`, this would lead to `"Col_a_b094"` I believe (which is not what the OP wants) – Gnueghoidune Mar 25 '22 at 06:10
@Gnueghoidune , correct. Only column names `Col_a_b1 Col_a_b2 Col_a_b3 Col_a_b4 Col_a_b5 Col_a_b6 Col_a_b7 Col_a_b8 Col_a_b9` should have 0before the numbers. – Ahir Bhairav Orai Mar 25 '22 at 06:14
Modified the answer. – Nad Pat Mar 25 '22 at 13:02

Gnueghoidune · Answer 2 · 2022-03-25T09:01:34.793

For a given dataframe called data:

colnames(data) <- sprintf("Col_a_b%02d", parse_number(colnames(data)))

%02d means a decimal integer, left padded, with zeros up to 2 digits.

Example

# Sample data
data = structure(list(Col_a_b1 = c("Name1", "Name2"), Col_a_b94 = c(1, 
2)), class = "data.frame", row.names = c(NA, -2L))

> data
  Col_a_b1 Col_a_b94
1    Name1         1
2    Name2         2

colnames(data) <- sprintf("Col_a_b%02d", parse_number(colnames(data)))

> data
  Col_a_b01 Col_a_b94
1     Name1         1
2     Name2         2

score 0 · Answer 3 · answered Mar 25 '22 at 08:31

With a tidyverse approach:

library(tidyverse)

names <- c("Col_a_b1", "Col_a_b2", "Col_a_b3", "Col_a_b4", "Col_a_b5", "Col_a_b6", "Col_a_b7", "Col_a_b8", "Col_a_b9", "Col_a_b10", "Col_a_b11")

names %>% 
  str_split("(?<=Col_a_b)(?=\\d+)") %>% 
  map_chr(~ str_c(.x[1], str_pad(.x[2], width = 2, pad = "0")))

#>  [1] "Col_a_b01" "Col_a_b02" "Col_a_b03" "Col_a_b04" "Col_a_b05" "Col_a_b06"
#>  [7] "Col_a_b07" "Col_a_b08" "Col_a_b09" "Col_a_b10" "Col_a_b11"

sequential column names add 0

3 Answers3