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

Question

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

Answer 1

One option is to use lapply and class. For example:

> foo <- data.frame(c("a", "b"), c(1, 2)) > names(foo) <- c("SomeFactor", "SomeNumeric") > lapply(foo, class) $SomeFactor [1] "factor"  $SomeNumeric [1] "numeric" 

Another option is str:

> str(foo) 'data.frame':   2 obs. of  2 variables:  $ SomeFactor : Factor w/ 2 levels "a","b": 1 2  $ SomeNumeric: num  1 2 

Answer 2

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.