I want to replace those values of df1$colB with values from df2$replacement where df1$colB is equal to df2$matches.
df1 <- data.frame(colA = 1:10, colB = letters[1:10])
df2 <- data.frame(matches= letters[4:1], replacement= LETTERS [4:1])
The result should look like df3:
df3 <- data.frame(colA =1:10, colB = c(LETTERS[1:4],letters[5:10]))
I'd like to avoid a for-loop solution for this task.
You could use the chartr function in base R.
# read in data with character vectors, not factors
df1 <- data.frame(colA = 1:10, colB = letters[1:10], stringsAsFactors=F)
df2 <- data.frame(matches= letters[4:1], replacement= LETTERS [4:1], stringsAsFactors=F)
df3 <- data.frame(colA =1:10, colB = c(LETTERS[1:4],letters[5:10]), stringsAsFactors=F)
# replace the characters with the desired characters
df1$colB <- chartr(paste(df2$matches, collapse=""),
paste(df2$replacement, collapse=""), df1$colB)
According to the help file, `?chartr, the function
Translate(s) characters in character vectors
You can do a merge on df1 and df2, and then replace the colB value by the replacement:
library(dplyr)
merge(df1, df2, by.x = "colB", by.y = "matches", all.x = T) %>%
mutate(colB = ifelse(!is.na(replacement), replacement, colB)) %>%
select(colA, colB)
colA colB
1 1 A
2 2 B
3 3 C
4 4 D
5 5 e
6 6 f
7 7 g
8 8 h
9 9 i
10 10 j
