[R] How to show classes of all columns of a data frame?

[Marc Schwartz (via MN)]

On Tue, 2006-08-15 at 13:10 -0400, T Mu wrote:
> Hi all,
> 
> Suppose I have a data frame myDF, col A is factor, col B is numeric, col C
> is character. I can get their classes by
> 
> > class(myDF$A)
> 
> but is there a quick way to show what classes of all columns are? Thank you.
> 
> Tian

Depending upon the output format you desire:

> lapply(iris, class)
$Sepal.Length
[1] "numeric"

$Sepal.Width
[1] "numeric"

$Petal.Length
[1] "numeric"

$Petal.Width
[1] "numeric"

$Species
[1] "factor"


or

> sapply(iris, class)
Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species
   "numeric"    "numeric"    "numeric"    "numeric"     "factor"


See ?lapply and ?sapply


HTH,

Marc Schwartz