How to rename specific part of column names in R?-CodePudding

I have some column names as follows jan_20_5, feb_20_7, mar_20_3, apr_20_9, etc.

I have 12 such columns and would like to eliminate everything after the second "_" and append something common by groups of three so that it outputs something like the following: jan_20_winter, feb_20_winter, mar_20_winter, apr_20_spring, may_20_spring, jun_20_spring, jul_20_summer etc.

How can I go about this in an efficient manner in R?

Thank you in advance!

CodePudding user response：

You could use stringr, some regex finding the last digit in the string, and replace it with a vector of the seasons?

library(stringr)

# Fake data
df <- data.frame(matrix(ncol = 12, nrow = 0))
colnames(df) <- paste(month.abb, 20:31, 4:15, sep = "_")

# Replacement
names(df) <- str_replace(names(df),
                         "\\d $",
                         rep(c("winter", "spring", "summer", "autumn"), each = 3))

df

Output:

 [1] Jan_20_winter Feb_21_winter Mar_22_winter Apr_23_spring May_24_spring Jun_25_spring Jul_26_summer
 [8] Aug_27_summer Sep_28_summer Oct_29_autumn Nov_30_autumn Dec_31_autumn
<0 rows> (or 0-length row.names)

CodePudding user response：

Depending on the formatting, this may help you:

# example colnames
cn <- c("jan_20_5", "feb_20_7", "mar_20_3", "apr_20_9", "may_20_18", "jun_20_8", "jul_20_4", "aug_20_7", "sep_20_5", "oct_20_4")


labl <- setNames(
 gl(4,3, labels = c("winter", "spring", "summer", "fall")),
 tolower(month.abb)
)

paste0(gsub("(.*_)(.*)", "\\1", cn), labl[gsub("_.*", "", cn)])
#>  [1] "jan_20_winter" "feb_20_winter" "mar_20_winter" "apr_20_spring"
#>  [5] "may_20_spring" "jun_20_spring" "jul_20_summer" "aug_20_summer"
#>  [9] "sep_20_summer" "oct_20_fall"

^{Created on 2022-07-27 by the reprex package (v2.0.1)}

CodePudding user response：

You can make a simple mapping of tolower(month.abb) to season (in this example below I've mapped months 1:3, 4:6, 7:9, and 10:12 to winter, spring, summer, fall, but you may adjust this), and then replace the column names as below:

season=setNames(rep(c("winter","spring", "summer", "fall"),each=3),tolower(month.abb))

names(data) = sapply(str_remove(names(data),"_[0-9]{1,2}$"), \(k) {
  paste0(k,"_",season[[substr(k,1,3)]])
})