count

count(__data, *args, *, wt=None, sort=False, name=None, **kwargs)

Summarize data with the number of rows for each grouping of data.

Parameters

Name	Description	Default
`__data`	A DataFrame.	required
`*args`	The names of columns to be used for grouping. Passed to group_by.	`()`
`wt`	The name of a column to use as a weighted for each row.	`None`
`sort`	Whether to sort the results in descending order.	`False`
`**kwargs`	Creates a new named column, and uses for grouping. Passed to group_by.	`{}`

Examples

>>> from siuba import _, count, group_by, summarize, arrange
>>> from siuba.data import mtcars

>>> count(mtcars, _.cyl, high_mpg = _.mpg > 30)
   cyl  high_mpg   n
0    4     False   7
1    4      True   4
2    6     False   7
3    8     False  14

Use sort to order results by number of observations (in descending order).

>>> count(mtcars, _.cyl, sort=True)
   cyl   n
0    8  14
1    4  11
2    6   7

count is equivalent to doing a grouped summarize:

>>> mtcars >> group_by(_.cyl) >> summarize(n = _.shape[0]) >> arrange(-_.n)
   cyl   n
2    8  14
0    4  11
1    6   7