Merge pull request python-visualization#28 from adamrpah/expanded_color_support

Added expanded color support to 253 colors with a sequential colorbrewer...

Author: wrobstory

folium/folium.py

@@ -629,14 +629,15 @@ def json_style(style_cnt, line_color, line_weight, line_opacity,
  #D3 Color scale
  series = data[columns[1]]
  domain = threshold_scale or utilities.split_six(series=series)
- if len(domain) > 6:
- raise ValueError('The threshold scale must be of length <= 6')
+ if len(domain) > 253:
+ raise ValueError('The threshold scale must be of length <= 253')
  if not utilities.color_brewer(fill_color):
  raise ValueError('Please pass a valid color brewer code to '
  'fill_local. See docstring for valid codes.')
 
- palette = utilities.color_brewer(fill_color)
+ palette = utilities.color_brewer(fill_color, len(domain))
  d3range = palette[0: len(domain) + 1]
+ tick_labels = utilities.legend_scaler(domain)
 
  color_temp = self.env.get_template('d3_threshold.js')
  d3scale = color_temp.render({'domain': domain,
@@ -647,6 +648,7 @@ def json_style(style_cnt, line_color, line_weight, line_opacity,
  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})
  self.template_vars.setdefault('map_legends', []).append(legend)
 

folium/templates/d3_map_legend.js

@@ -12,7 +12,7 @@
  .scale(x)
  .orient("top")
  .tickSize(1)
- .tickValues(color.domain())
+ .tickValues({{ tick_labels }});
 
  var svg = d3.select(".legend.leaflet-control").append("svg")
  .attr("id", 'legend')
@@ -40,4 +40,4 @@
  g.call(xAxis).append("text")
  .attr("class", "caption")
  .attr("y", 21)
- .text('{{ caption }}');
+ .text('{{ caption }}');

folium/utilities.py

@@ -27,10 +27,101 @@ def get_templates():
  '''Get Jinja templates'''
  return Environment(loader=PackageLoader('folium', 'templates'))
 
+def legend_scaler(legend_values, max_labels=10.0):
+ '''
+ Downsamples the number of legend values so that there isn't a collision
+ of text on the legend colorbar (within reason). The colorbar seems to 
+ support ~10 entries as a maximum
+ '''
+ import math
+
+ if len(legend_values)<max_labels:
+ legend_ticks = legend_values
+ else:
+ spacer = int(math.ceil(len(legend_values)/max_labels))
+ legend_ticks = []
+ for i in legend_values[::spacer]:
+ legend_ticks += [i]
+ legend_ticks += ['']*(spacer-1)
+ return legend_ticks
+
+
+def linear_gradient(hexList, nColors):
+ """Given a list of hexcode values, will return a list of length
+ nColors where the colors are linearly interpolated between the
+ (r, g, b) tuples that are given.
+
+ Example:
+ linear_gradient([(0, 0, 0), (255, 0, 0), (255, 255, 0)], 100)
+ """
+ def _scale(start, finish, length, i):
+ """Return the value correct value of a number that is inbetween start
+ and finish, for use in a loop of length *length*"""
+ base=16
+
+ fraction = float(i) / (length - 1)
+ raynge = int(finish, base) - int(start, base)
+ thex = hex(int(int(start, base) + fraction * raynge)).split('x')[-1]
+ if len(thex)!=2:
+ thex ='0' + thex
+ return thex
+
 
-def color_brewer(color_code):
+ allColors = []
+ # separate (r, g, b) pairs
+ for start, end in zip(hexList[:-1], hexList[1:]):
+ # linearly intepolate between pair of hex ###### values and add to list
+ nInterpolate = 765 
+ for index in range(nInterpolate):
+ r = _scale(start[1:3], end[1:3], nInterpolate, index)
+ g = _scale(start[3:5], end[3:5], nInterpolate, index)
+ b = _scale(start[5:7], end[5:7], nInterpolate, index)
+ allColors.append(''.join(['#',r,g,b]))
+
+ # pick only nColors colors from the total list
+ result = []
+ for counter in range(nColors):
+ fraction = float(counter) / (nColors - 1)
+ index = int(fraction * (len(allColors) - 1)) 
+ result.append(allColors[index])
+ return result
+
+
+def color_brewer(color_code, n=6):
  '''Generate a colorbrewer color scheme of length 'len', type 'scheme.
  Live examples can be seen at http://colorbrewer2.org/'''
+ maximum_n = 253
+
+ scheme_info = {'BuGn': 'Sequential',
+ 'BuPu': 'Sequential',
+ 'GnBu': 'Sequential',
+ 'OrRd': 'Sequential',
+ 'PuBu': 'Sequential',
+ 'PuBuGn': 'Sequential',
+ 'PuRd': 'Sequential',
+ 'RdPu': 'Sequential',
+ 'YlGn': 'Sequential',
+ 'YlGnBu': 'Sequential',
+ 'YlOrBr': 'Sequential',
+ 'YlOrRd': 'Sequential',
+ 'BrBg': 'Diverging',
+ 'PiYG': 'Diverging',
+ 'PRGn': 'Diverging',
+ 'PuOr': 'Diverging',
+ 'RdBu': 'Diverging',
+ 'RdGy': 'Diverging',
+ 'RdYlBu': 'Diverging',
+ 'RdYlGn': 'Diverging',
+ 'Spectral': 'Diverging',
+ 'Accent': 'Qualitative', 
+ 'Dark2': 'Qualitative',
+ 'Paired': 'Qualitative',
+ 'Pastel1': 'Qualitative',
+ 'Pastel2': 'Qualitative',
+ 'Set1': 'Qualitative',
+ 'Set2': 'Qualitative',
+ 'Set3': 'Qualitative',
+ }
 
  schemes = {'BuGn': ['#EDF8FB', '#CCECE6', '#CCECE6', '#66C2A4', '#41AE76',
  '#238B45', '#005824'],
@@ -55,9 +146,44 @@ def color_brewer(color_code):
  'YlOrBr': ['#FFFFD4', '#FEE391', '#FEC44F', '#FE9929', '#EC7014',
  '#CC4C02', '#8C2D04'],
  'YlOrRd': ['#FFFFB2', '#FED976', '#FEB24C', '#FD8D3C', '#FC4E2A',
- '#E31A1C', '#B10026']}
+ '#E31A1C', '#B10026'],
+ 'BrBg': ['#8c510a', '#d8b365', '#f6e8c3', '#c7eae5', '#5ab4ac', '#01665e'],
+ 'PiYG': ['#c51b7d', '#e9a3c9', '#fde0ef', '#e6f5d0', '#a1d76a', '#4d9221'],
+ 'PRGn': ['#762a83', '#af8dc3', '#e7d4e8', '#d9f0d3', '#7fbf7b', '#1b7837'],
+ 'PuOr': ['#b35806', '#f1a340', '#fee0b6', '#d8daeb', '#998ec3', '#542788'],
+ 'RdBu': ['#b2182b', '#ef8a62', '#fddbc7', '#d1e5f0', '#67a9cf', '#2166ac'],
+ 'RdGy': ['#b2182b', '#ef8a62', '#fddbc7', '#e0e0e0', '#999999', '#4d4d4d'],
+ 'RdYlBu': ['#d73027', '#fc8d59', '#fee090', '#e0f3f8', '#91bfdb', '#4575b4'],
+ 'RdYlGn': ['#d73027', '#fc8d59', '#fee08b', '#d9ef8b', '#91cf60', '#1a9850'],
+ 'Spectral': ['#d53e4f' '#fc8d59' '#fee08b' '#e6f598' '#99d594' '#3288bd'],
+ 'Accent': ['#7fc97f', '#beaed4', '#fdc086', '#ffff99', '#386cb0', '#f0027f'],
+ 'Dark2': ['#1b9e77', '#d95f02', '#7570b3', '#e7298a', '#66a61e', '#e6ab02'],
+ 'Paired': ['#a6cee3', '#1f78b4', '#b2df8a', '#33a02c', '#fb9a99', '#e31a1c'],
+ 'Pastel1': ['#fbb4ae', '#b3cde3', '#ccebc5', '#decbe4', '#fed9a6', '#ffffcc'],
+ 'Pastel2': ['#b3e2cd', '#fdcdac', '#cbd5e8', '#f4cae4', '#e6f5c9', '#fff2ae'],
+ 'Set1': ['#e41a1c', '#377eb8', '#4daf4a', '#984ea3', '#ff7f00', '#ffff33'],
+ 'Set2': ['#66c2a5', '#fc8d62', '#8da0cb', '#e78ac3', '#a6d854', '#ffd92f'],
+ 'Set3': ['#8dd3c7', '#ffffb3', '#bebada', '#fb8072', '#80b1d3', '#fdb462'],
+ }
+
+ #Raise an error if the n requested is greater than the maximum
+ if n > maximum_n:
+ raise ValueError("The maximum number of colors in a ColorBrewer sequential color series is 253")
+
+ #Only if n is greater than six do we interpolate values
+ if n > 6:
+ if color_code not in schemes:
+ color_scheme= None
+ else:
+ #Check to make sure that it is not a qualitative scheme
+ if scheme_info[color_code]=='Qualitative':
+ raise ValueError("Expanded color support is not available for Qualitative schemes, restrict number of colors to 6")
+ else:
+ color_scheme = linear_gradient(schemes.get(color_code), n)
+ else:
+ color_scheme = schemes.get(color_code, None)
+ return color_scheme
 
- return schemes.get(color_code, None)
 
 
 def transform_data(data):