CODEWITHSUNDEEP
rlistcharacter
useR
useR

Reputation: 179

check a data.frame column (character) against 4 lists

I want to check a word (in a column in a data-frame) against 4 lists (a, b, c, d):

if df$word is in a then df$code <- 1
if df$word is in b then df$code <- 2
if df$word is in c then df$code <- 3
if df$word is in d then df$code <- 4

if df$word is in a & b then df$code <- 1 2
if df$word is in a & c then df$code <- 1 3
if df$word is in a & d then df$code <- 1 4
if df$word is in b & c then df$code <- 2 3
if df$word is in b & d then df$code <- 2 4
if df$word is in c & d then df$code <- 3 4

etc.

What is the most efficient way to do so?

Example

df <- data.frame(word = c("book", "worm", "digital", "context"))

a <- c("book", "context")
b <- c("book", "worm", "context")
c <- c("digital", "worm", "context")
d <- c("context")

Expected output:

book    1 2
worm    2 3
digital 3
context 1 2 3 4

Upvotes: 1

Views: 45

Answers (3)

Uwe
Uwe

Reputation: 42544

This can also be accomplished in two steps:

  1. Combine the four lists and reshape into long format
  2. Aggregate while joing with df

using data.table:

library(data.table)
long <-setDT(melt(list(a, b, c, d), value.name = "word"))
long[setDT(df), on = "word", by = .EACHI, .(code = toString(L1))][]

      word       code
1:    book       1, 2
2:    worm       2, 3
3: digital          3
4: context 1, 2, 3, 4

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 388982

We can use a double sapply loop where for every element in the data frame we check in which list element it is present and get the corresponding list number.

lst <- list(a, b, c, d)
df$output <- sapply(df$V1, function(x) paste0(which(sapply(lst, 
                           function(y) any(grepl(x,y)))), collapse = ","))

df
#       V1  output
#1    book     1,2
#2    worm     2,3
#3 digital       3
#4 context 1,2,3,4

data

df <- read.table(text = "book
      worm
      digital
      context")

Upvotes: 2

TC Zhang
TC Zhang

Reputation: 2797

Try this:

df <- data.frame(x =c("book", "worm","digital", "context"))

a <- c("book", "context")
b<- c("book", "worm", "context")
c <- c("digital", "worm", "context")
d <- c("context")


anno <- function(x){
  rslt = ""
  if (x %in% a) rslt =paste0(rslt," 1")
  if (x %in% b) rslt =paste0(rslt," 2")
  if (x %in% c) rslt =paste0(rslt," 3")
  if (x %in% d) rslt =paste0(rslt," 4")
  return(stringr::str_trim(rslt))
}

df$code <- sapply(df$x, anno)
df
#>         x    code
#> 1    book     1 2
#> 2    worm     2 3
#> 3 digital       3
#> 4 context 1 2 3 4

Created on 2018-08-17 by the reprex package (v0.2.0.9000).

Upvotes: 1

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