apply function error

Question

[j_weld]

I have this dataframe and when i'm trying to count sum of columns I'm getting this error message:

 Error in FUN(X[[i]], ...) : invalid 'type' (character) of argument.

[cpad0112]

try this:

data |>
    apply(2, as.numeric) |>
    colSums()

Answer 1

[rpolicastro]

It's telling you that one or more of your columns is formatted as a character instead of numeric, so you need to convert them first.

data[] <- lapply(data, as.numeric)

If you're curious which columns are characters.

colnames(data[, sapply(data, is, "character")])

[seidel]

And FWIW, if you've fixed the type problem, there is a function for summing columns called colSums().

Answer 2

[jv]

the error invalid 'type' (character) is telling you that the information in the cells of your data frame are characters (i.e. text) not numbers (aka numerics). R can be picky about the "type" and in this case since you can't sum letters you get this error.

First convert your data.frame columns to numerics, one option is:

df <- apply(df, 2, function(x) as.numeric(x))
sums <- apply(df, 2, sum)

though personally I tend to go with colSums for this sort of operation.