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I have 77 numeric variables which are technically ordered factor variables. I know that I can do the below for changing the first column of data frame df into an ordered factor variable:

df[,1]<-as.ordered(df[,1])

But is there a quick way that I can turn the entire data frame of 77 variables into a data frame of ordered factor variables?

Thank you,

chico0913
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2 Answers2

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We can loop over the dataset columns with lapply, apply the function and assign it back to the original dataset

df[] <- lapply(df, as.ordered)

Or with dplyr

library(dplyr)
df <- df %>%
         mutate_all(as.ordered)
akrun
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For such cases is for loop good and fast enough. 

for (i in 1:ncol(df)) df[, i] <- as.factor(df[, i])

(Very likely - from my experience - faster than any lapply or any apply-family solution - because avoiding building lists which are very slow in R.)

For 1:ncol(df) you can also use seq_along(df).

Gwang-Jin Kim
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