How to use sapply function on specific columns?

Question

I have a function that removes columns without a given number of unique values. This command does it for the whole data frame. How would I do this on specific columns? Say columns 3 to 50? Thanks.

ms_10 <- ms_10[, sapply(ms_10, function(col) length(unique(col))) > 440]

Answer 1

You can subset the data first and then apply the same function.

new_data <- ms_10[3:50]
new_data <- new_data[, sapply(new_data, function(col) length(unique(col))) > 440]

If you don't want to create temporary variable ( new_data ).

ms_10[3:50][, sapply(ms_10[3:50], function(col) length(unique(col))) > 440]

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We can also use dplyr :

library(dplyr)

ms_10 %>%
  select(3:50) %>%
  select(where(~n_distinct(.) > 440))

Answer 2

We can use

Filter(function(x) length(unique(x)) > 440, ms_10[3:50])