Replace specific value in column in R

Question

I have a variable in a data frame which consists of either 5 or 6 digits/characters. Those values in the variable with 5 digits are all numbers e.g. 27701 those with 6 digits however all have a character 'C' preceding the numbers e.g. C22701.

How can I replace the 'C' characters with 999 for example?

I have tried:

replace(data$varname,'C',999)

Any ideas folks?

data$varname <- gsub('C', '999', data$varname) maybe? If varname is a factor, it could cause problems though — David Arenburg
– David Arenburg, Commented Sep 2, 2014 at 12:12
What format do you want the variable in the end? Character? Factor? Numeric? — CephBirk
– CephBirk, Commented Sep 2, 2014 at 13:13

CephBirk · Accepted Answer · 2014-09-02 13:43:18Z

data$varname <- as.numeric(gsub('C', '999', data$varname)) should do the trick, I think. Assuming you want a numeric vector in the end. If you want a character vector, then you can leave as.numeric off.

Rich Scriven · Accepted Answer · 2014-09-02 13:21:30Z

You can use a substring to remove the first letter, and paste0 to add 999 to it.

> x <- c("C000", "P1745") > paste0("999", substring(x,2)) # [1] "999000" "9991745"

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