BUG: Enable plotting with PeriodIndex with arbitrary frequencies, resolves #14763

pandas/plotting/_timeseries.py

@@ -262,7 +262,7 @@ def _get_index_freq(data):
 def _maybe_convert_index(ax, data):
     # tsplot converts automatically, but don't want to convert index
     # over and over for DataFrames
-    if isinstance(data.index, ABCDatetimeIndex):
+    if isinstance(data.index, (ABCDatetimeIndex, ABCPeriodIndex)):
         freq = getattr(data.index, 'freq', None)
 
         if freq is None:
@@ -279,7 +279,10 @@ def _maybe_convert_index(ax, data):
         freq = get_base_alias(freq)
         freq = frequencies.get_period_alias(freq)
 
-        data = data.to_period(freq=freq)
+        if isinstance(data.index, ABCDatetimeIndex):
+            data = data.to_period(freq=freq)
+        elif isinstance(data.index, ABCPeriodIndex):
+            data.index = data.index.asfreq(freq=freq)
     return data
 
 

pandas/tests/plotting/test_datetimelike.py

@@ -1,5 +1,6 @@
 """ Test cases for time series specific (freq conversion, etc) """
 from datetime import date, datetime, time, timedelta
+import itertools
 import pickle
 import sys
 
@@ -33,6 +34,13 @@ def setup_method(self, method):
         self.period_df = [DataFrame(np.random.randn(len(x), 3), index=x,
                                     columns=['A', 'B', 'C'])
                           for x in idx]
+        mults = [1, 23]  # setup periods with multiples of freq.rule_code
+        freq = [str(mlt) + frq for frq, mlt in itertools.product(freq, mults)]
+        idx = [period_range('12/31/1999', freq=x, periods=100) for x in freq]
+        self.period_mlt_ser = [Series(np.random.randn(len(x)), x) for x in idx]
+        self.period_mlt_df = [DataFrame(np.random.randn(len(x), 3), index=x,
+                                        columns=['A', 'B', 'C'])
+                              for x in idx]
 
         freq = ['S', 'T', 'H', 'D', 'W', 'M', 'Q-DEC', 'A', '1B30Min']
         idx = [date_range('12/31/1999', freq=x, periods=100) for x in freq]
@@ -210,6 +218,11 @@ def test_line_plot_period_series(self):
         for s in self.period_ser:
             _check_plot_works(s.plot, s.index.freq)
 
+    @pytest.mark.slow
+    def test_line_plot_period_mlt_series(self):
+        for s in self.period_mlt_ser:
+            _check_plot_works(s.plot, s.index.freq.rule_code)
+
     @pytest.mark.slow
     def test_line_plot_datetime_series(self):
         for s in self.datetime_ser:
@@ -220,6 +233,12 @@ def test_line_plot_period_frame(self):
         for df in self.period_df:
             _check_plot_works(df.plot, df.index.freq)
 
+    @pytest.mark.slow
+    def test_line_plot_period_mlt_frame(self):
+        for df in self.period_mlt_df:
+            freq = df.index.asfreq(df.index.freq.rule_code).freq
+            _check_plot_works(df.plot, freq)
+
     @pytest.mark.slow
     def test_line_plot_datetime_frame(self):
         for df in self.datetime_df: