Changing Columns 22-300 from double (or other type) into numeric

Question

I have a huge dataset and some columns are text. Upon importing the Excel file and using preview, I can manually change the first 50 columns to numeric, if this applies. But, there are still 250 more columns I need to change to numeric. How would I use R code to change all columns from column 22 through column 300 to numeric?

Answer 1

One way:

mydf[22:300] <- lapply(mydf[22:300], as.numeric)

Answer 2

We can use type.convert (assuming the columns are character class)

df1[22:300] <- type.convert(df1[22:300], as.is = TRUE)

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Also, with mutate_at from dplyr

library(tidyverse)
df1 %>%
     mutate_at(22:300, type_convert)