Apply a function to all the elements of a data frame

r dataframe apply
Deena picture Deena · Oct 27, 2016 · Viewed 16.5k times · Source

I am trying to apply some transformations to all the elements in a dataframe.

When using the regular apply functions, I get a matrix back and not a dataframe. Is there a way to get a dataframe directly without adding as.data.frame to each line?

df = data.frame(a = LETTERS[1:5], b = LETTERS[6:10])

apply(df, 1, tolower) #Matrix
apply(df, 2, tolower) #Matrix
sapply(df, tolower)   #Matrix

as.data.frame(sapply(df, tolower)) # Can I avoid "as.data.frame"?

Answer

akrun picture akrun · Oct 27, 2016

We can use lapply and assign it back to 'df'

df[] <- lapply(df, tolower)

The [] preserves the same structure as the original dataset. Using apply convert it to a matrix and that is not recommended.

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