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rstringconcatenationnumeric

Concatenate string element and number into same cell in dataframe r

If I have this dataframe:

df <- data.frame(col1 = c(NA,NA,NA,"Doggy",NA,NA,"Pound"),col2 = c(1:7))

Let's say I want to check if there is not a NA-value in col1 and add the corresponding number from the other column if that is true, I'd write this:

for (i in 1:nrow(df)){
  if (is.na(df[i,1]) == FALSE){
    #add the df[i,2] number to the df[i,1] string. 
  }

How should I go about concatenating the string with the numeric?

Solution

  • Here df[i,1] <- paste(df[i,1], df[i,2]) will fit.

    for (i in 1:nrow(df)){
  if (is.na(df[i,1]) == FALSE) {
    df[i,1] <- paste(df[i,1], df[i,2])
  }
}
df
#     col1 col2
#1    <NA>    1
#2    <NA>    2
#3    <NA>    3
#4 Doggy 4    4
#5    <NA>    5
#6    <NA>    6
#7 Pound 7    7

    I would do something like:

    i <- which(!is.na(df[,1]))
df[i,1] <- do.call(paste, df[i,])