Fixed precision error; upgrade ipython; added second axis example

chartify/_core/plot.py

@@ -37,7 +37,11 @@ def __init__(self, chart, y_range_name="default"):
     @staticmethod
     def _axis_format_precision(max_value, min_value):
         difference = abs(max_value - min_value)
-        precision = abs(int(np.floor(np.log10(difference)))) + 1
+        if difference:
+            precision = abs(int(np.floor(np.log10(difference)))) + 1
+        else:
+            precision = 1
+        print(precision)
         zeros = ''.join(['0']*precision)
         return "0,0.[{}]".format(zeros)
 

chartify/examples.py

@@ -960,6 +960,58 @@ def _heatmap_example_1(average_price_by_fruit_and_country):
 plot_heatmap.__doc__ = _core.plot.PlotCategoricalXY.heatmap.__doc__
 
 
+@_print_source
+def chart_second_axis():
+    """
+    Docstring
+    """
+    import chartify
+
+    # Generate example data
+    data = chartify.examples.example_data()
+
+    # Sum price grouped by date
+    price_by_date = (
+        data.groupby('date')['total_price'].sum()
+        .reset_index()  # Move 'date' from index to column
+        )
+    price_by_date['triple_total_price'] = price_by_date['total_price'] * 3
+    price_by_date = price_by_date.sort_values('date')
+    print(price_by_date.head())
+    """Print break"""
+    _second_axis_example(price_by_date)
+
+
+@_print_source
+def _second_axis_example(price_by_date):
+    """Docstring"""
+    # Initialize chart with second_y_axis=True
+    ch = chartify.Chart(blank_labels=True,
+                        x_axis_type='datetime',
+                        y_axis_type='linear',
+                        second_y_axis=True)
+    ch.set_title("Second Y axis")
+    # Plot the first axis
+    ch.plot.line(
+        data_frame=price_by_date,
+        x_column='date',
+        y_column='total_price')
+    ch.axes.set_yaxis_range(0, 50)
+    ch.axes.set_yaxis_label('First axis label')
+    ch.axes.set_yaxis_tick_format('0a')
+
+    # Plot the second axis
+    ch.second_axis.axes.set_yaxis_range(0, 80)
+    ch.second_axis.axes.set_yaxis_label('Second axis label')
+    ch.second_axis.plot.line(
+        # Data must be sorted by x column
+        data_frame=price_by_date,
+        x_column='date',
+        y_column='triple_total_price')
+    ch.second_axis.axes.set_yaxis_tick_format('0.0')
+    ch.show(_OUTPUT_FORMAT)
+
+
 @_print_source
 def style_color_palette_accent():
     """

requirements_dev.txt

@@ -12,7 +12,7 @@ commonmark==0.5.4
 recommonmark==0.4.0
 
 prompt-toolkit==1.0.15
-ipython==6.5.0
+ipython==7.2.0
 pytest==3.2.3
 pytest-cov==2.5.1
 coverage-badge==0.2.0