ENH: crosstab prototype function, API needs fleshing out, GH #170

Author: wesm

RELEASE.rst

@@ -70,6 +70,8 @@ pandas 0.7.0
     NA values inserted in non-numeric columns (GH #614)
   - Can pass a list of dicts or Series to ``DataFrame.append`` to concatenate
     multiple rows (GH #464)
+  - Add ``level`` argument to ``DataFrame.xs`` for selecting data from other
+    MultiIndex levels (GH #371, GH #629)
 
 **API Changes**
 

pandas/__init__.py

@@ -30,4 +30,4 @@
 from pandas.util.testing import debug
 
 from pandas.tools.merge import merge, concat
-from pandas.tools.pivot import pivot_table
+from pandas.tools.pivot import pivot_table, crosstab

pandas/tools/pivot.py

@@ -165,3 +165,31 @@ def _convert_by(by):
         by = list(by)
     return by
 
+def crosstab(rows, columns):
+    """
+    Compute a simple cross-tabulation of two (or more) factors
+
+    Parameters
+    ----------
+    rows :
+    columns :
+
+    Returns
+    -------
+    crosstab : DataFrame
+    """
+    rname = cname = None
+    if isinstance(rows, Series):
+        rname = rows.name
+
+    if isinstance(columns, Series):
+        cname = columns.name
+
+    df = DataFrame({'rows' : rows, 'columns' : columns})
+    table = df.groupby(['rows', 'columns']).size()
+
+    result = table.unstack()
+    result.columns.name = cname
+    result.index.name = rname
+
+    return result