How to use pandas crosstab in python?

Compute a simple cross tabulation of two (or more) factors.

By default, computes a frequency table of the factors unless an array of values and an aggregation function are passed.

Values to group by in the rows.

Values to group by in the columns.

Array of values to aggregate according to the factors. Requires aggfunc be specified.

If passed, must match number of row arrays passed.

If passed, must match number of column arrays passed.

If specified, requires values be specified as well.

Add row/column margins (subtotals).

Name of the row/column that will contain the totals when margins is True.

Do not include columns whose entries are all NaN.

Normalize by dividing all values by the sum of values.

• If passed ‘all’ or True, will normalize over all values.

• If passed ‘index’ will normalize over each row.

• If passed ‘columns’ will normalize over each column.

• If margins is True, will also normalize margin values.

Cross tabulation of the data.

Notes

Any Series passed will have their name attributes used unless row or column names for the cross-tabulation are specified.

Any input passed containing Categorical data will have all of its categories included in the cross-tabulation, even if the actual data does not contain any instances of a particular category.

In the event that there aren’t overlapping indexes an empty DataFrame will be returned.

Reference the user guide for more examples.

Examples

>>> a = np.array(["foo", "foo", "foo", "foo", "bar", "bar",
...               "bar", "bar", "foo", "foo", "foo"], dtype=object)
>>> b = np.array(["one", "one", "one", "two", "one", "one",
...               "one", "two", "two", "two", "one"], dtype=object)
>>> c = np.array(["dull", "dull", "shiny", "dull", "dull", "shiny",
...               "shiny", "dull", "shiny", "shiny", "shiny"],
...              dtype=object)
>>> pd.crosstab(a, [b, c], rownames=['a'], colnames=['b', 'c'])
b   one        two
c   dull shiny dull shiny
a
bar    1     2    1     0
foo    2     2    1     2

Here ‘c’ and ‘f’ are not represented in the data and will not be shown in the output because dropna is True by default. Set dropna=False to preserve categories with no data.

>>> foo = pd.Categorical(['a', 'b'], categories=['a', 'b', 'c'])
>>> bar = pd.Categorical(['d', 'e'], categories=['d', 'e', 'f'])
>>> pd.crosstab(foo, bar)
col_0  d  e
row_0
a      1  0
b      0  1
>>> pd.crosstab(foo, bar, dropna=False)
col_0  d  e  f
row_0
a      1  0  0
b      0  1  0
c      0  0  0