How do I get the classes of all columns in a data frame

Question

What is an easy way to find out what class each column is in a data frame is

User · Accepted Answer

One option is to use lapply and class  For example    gt  foo  lt - data frame c  a    b    c 1  2    gt  names foo   lt - c  SomeFactor    SomeNumeric    gt  lapply foo  class   SomeFactor  1   factor    SomeNumeric  1   numeric    Another option is str    gt  str foo   data frame     2 obs  of  2 variables     SomeFactor   Factor w  2 levels  a   b   1 2    SomeNumeric  num  1 2

User · Answer

You can simple make use of lapply or sapply builtin functions   lapply will return you a list -   lapply dataframe class    while sapply will take the best possible return type ex  Vector etc -   sapply dataframe class    Both the commands will return you all the column names with their respective class

User · Answer

I wanted a more compact output than the great answers above using lapply  so here s an alternative wrapped as a small function    Example data df  lt -     data frame          w   seq int 10           x   LETTERS seq int 10            y   factor letters seq int 10             z   seq              as POSIXct  2020-01-01                as POSIXct  2020-10-01                length out   10                    Function returning compact column classes col classes  lt - function df        t as data frame lapply df  function x  paste class x   collapse                Return example data s column classes col classes df       1              w  quot integer quot         x  quot character quot       y  quot factor quot          z  quot POSIXct POSIXt quot

User · Answer

You can use purrr as well  which is similar to apply family functions  as data frame purrr  map chr mtcars  class   purrr  map df mtcars  class

User · Answer

Hello was looking for the same  and it could be also unlist lapply mtcars class

[r] How do I get the classes of all columns in a data frame?

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