Get value from other column based on value of a column

Question

For each row in a data frame I want to copy a value from one column to another depending on a value in third column.

I tried to do it with a combined for loop and if fun

Answer 1

Try the following:

condition <- c("1","2","2","1","2","","3","3")
SZ01 <- c("1","1","1","1","1","","1","1")
SZ02 <- c("2","2","2","2","2","","2","2")
SZ03 <- c("3","3","3","3","3","","3","3")


df <- data.frame(cbind(condition,SZ01,SZ02,SZ03), stringsAsFactors = F)

df$retribution <- ifelse(df$condition == "1", df$SZ01,
                         ifelse(df$condition == "2", df$SZ02,
                            ifelse(df$condition == "3", df$SZ03, "missing")))

df$special_prevention <- ifelse(df$condition == "1", df$SZ02, 
                                ifelse(df$condition == "2", df$SZ03,
                                       ifelse(df$condition == "3", df$SZ01, "missing")))

df$general_prevention <- ifelse(df$condition == "1", df$SZ03, 
                                ifelse(df$condition == "2", df$SZ01,
                                       ifelse(df$condition == "3", df$SZ02, "missing"))))

Output:

df
  condition SZ01 SZ02 SZ03 retribution special_prevention general_prevention
1         1    1    2    3           1                  2                  3
2         2    1    2    3           2                  3                  1
3         2    1    2    3           2                  3                  1
4         1    1    2    3           1                  2                  3
5         2    1    2    3           2                  3                  1
6                              missing            missing            missing
7         3    1    2    3           3                  1                  2
8         3    1    2    3           3                  1                  2