introduce free scale for geo_json

Author: koldunovn

folium/folium.py

@@ -737,7 +737,7 @@ def geo_json(self, geo_path=None, geo_str=None, data_out='data.json',
                  data=None, columns=None, key_on=None, threshold_scale=None,
                  fill_color='blue', fill_opacity=0.6, line_color='black',
                  line_weight=1, line_opacity=1, legend_name=None,
-                 topojson=None, reset=False):
+                 topojson=None, reset=False, freescale=False):
         """Apply a GeoJSON overlay to the map.
 
         Plot a GeoJSON overlay on the base map. There is no requirement
@@ -804,6 +804,9 @@ def geo_json(self, geo_path=None, geo_str=None, data_out='data.json',
             keyword argument will enable conversion to GeoJSON.
         reset: boolean, default False
             Remove all current geoJSON layers, start with new layer
+        freescale: if True use free format for the scale, where min and max values
+            are taken from the data. It also allow to plot allow to plot values < 0 
+            and float legend labels.
 
         Output
         ------
@@ -892,8 +895,9 @@ def json_style(style_cnt, line_color, line_weight, line_opacity,
 
             # D3 Color scale.
             series = data[columns[1]]
-            if threshold_scale and len(threshold_scale) > 6:
-                raise ValueError
+            if freescale == False:
+                if threshold_scale and len(threshold_scale) > 6:
+                    raise ValueError
             domain = threshold_scale or utilities.split_six(series=series)
             if len(domain) > 253:
                 raise ValueError('The threshold scale must be length <= 253')
@@ -913,9 +917,21 @@ def json_style(style_cnt, line_color, line_weight, line_opacity,
             # Create legend.
             name = legend_name or columns[1]
             leg_templ = self.env.get_template('d3_map_legend.js')
-            legend = leg_templ.render({'lin_max': int(domain[-1]*1.1),
-                                       'tick_labels': tick_labels,
-                                       'caption': name})
+
+            if not freescale:
+                legend = leg_templ.render({'lin_min': 0,
+                           'lin_max': int(domain[-1]*1.1),
+                           'tick_labels': tick_labels,
+                           'caption': name})
+
+
+            else:
+                legend = leg_templ.render({'lin_min':  domain[0],
+                                           'lin_max':  domain[-1],
+                                           'tick_labels': tick_labels,
+                                           'caption': name})
+
+            
             self.template_vars.setdefault('map_legends', []).append(legend)
 
             # Style with color brewer colors.

folium/templates/d3_map_legend.js

@@ -5,7 +5,7 @@
     legend.addTo(map);
 
     var x = d3.scale.linear()
-    .domain([0, {{ lin_max }}])
+    .domain([{{ lin_min }}, {{ lin_max }}])
     .range([0, 400]);
 
     var xAxis = d3.svg.axis()

folium/utilities.py

@@ -273,7 +273,7 @@ def type_check(value):
     return json_data
 
 
-def split_six(series=None):
+def split_six(series=None, freescale=False):
     """
     Given a Pandas Series, get a domain of values from zero to the 90%
     quantile rounded to the nearest order-of-magnitude integer.
@@ -302,10 +302,14 @@ def base(x):
         else:
             return 0
 
-    quants = [0, 50, 75, 85, 90]
     # Some weirdness in series quantiles a la 0.13.
     arr = series.values
-    return [base(np.percentile(arr, x)) for x in quants]
+    if not freescale:
+        quants = [0, 50, 75, 85, 90]
+        return [base(np.percentile(arr, x)) for x in quants]
+    else:
+        quants = [0, 25, 50, 75, 85, 90]
+        return [np.percentile(arr, x) for x in quants]
 
 
 def write_png(array):