Alternative to loop ifelse() for vector data

Question

I have a price dataframe dat and a second dataframe with currencies cur. What i want to do is to transform every non-EUR price in dat into

Answer 1

The problem with your code is that you are comparing a vector against a character in if (dat$Nation == cur$Nation[i]), so the error tells you that it will only compare the first element of dat$Nation with cur$Nation[i].

In R, for-loops are often not necessary (and slow). You could do for example the following:

dat$conv <- cur$Rate[match(dat$Nation,cur$Nation)] # add the conversion factor
dat$PriceE <- ifelse(is.na(dat$conv), dat$Price, dat$Price * dat$conv)
dat$conv <- NULL

Output:

  Nation Price PriceE
1     AT    10 10.000
2     AT    12 12.000
3     BE    15 15.000
4     BG    30 15.300
5     BG    40 20.400
6     CZ   200  7.836

Hope this helps!