CODEWITHSUNDEEP
rstringcountstrsplitpreserve
Sarah
Sarah

Reputation: 463

Counting first letter of string and showing how many times it appears, but not in alphabetical order in R

I currently have this code written to count how many times the first letter of a code appears in a specific column in a table.

#a test data frame    
test <- data.frame("State" = c("PA", "RI", "SC"), "Code1" = c("EFGG, AFGG", "SSAG", "AFGG, SSAG"))

#code to count method codes
test[] <- lapply(test, as.character)


test_counts <- sapply(strsplit(test$Code1, ",\\s+"), function(x) {
  tab <- table(substr(x, 1, 1)) # Create a table of the first letters
  paste0(names(tab), tab, collapse = ", ") # Paste together the letter w/ the number and collapse 
them
} )

#example of output
[1] "A1, E1" "S1"     "A1, S1"

Everything about this current code is perfect, except I would like R to not output the counts in alphabetical order. I would like it to preserve the order of codes. So this is how I would like the output to look:

 [1] "E1, A1", "S1", "A1, S1"

Thank you!!

Upvotes: 1

Views: 164

Answers (2)

akrun
akrun

Reputation: 887911

Another option with tidyverse. We could split the 'Code1' with separate_rows, get the count and do a group_by paste after arrangeing the rows based on the frequency column

library(dplyr)
library(tidyr)
test %>% 
    separate_rows(Code1) %>%
    mutate(Code1 = substr(Code1, 1, 1)) %>%
    count(State, Code1) %>% 
    arrange(State, n) %>% 
    unite(Code1, Code1, n, sep="") %>% 
    group_by(State) %>% 
    summarise(Code1 = toString(Code1), .groups = 'drop') %>% 
    pull(Code1)
#[1] "A1, E1" "S1"     "A1, S1"

Upvotes: 0

ThomasIsCoding
ThomasIsCoding

Reputation: 102740

Here is a base R option using factor to address the issue

sapply(
  strsplit(test$Code1, ", "),
  function(x) {
    toString(
      do.call(
        paste0,
        rev(stack(table(factor(u<-substr(x, 1, 1),levels = unique(u)))))
      )
    )
  }
)

which gives

[1] "E1, A1" "S1"     "A1, S1"

Upvotes: 1

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