Remove split_six utility function (#161)

Author: Conengmo

branca/utilities.py

@@ -18,11 +18,6 @@
 
 from jinja2 import Environment, PackageLoader
 
-try:
-    import pandas as pd
-except ImportError:
-    pd = None
-
 try:
     import numpy as np
 except ImportError:
@@ -203,39 +198,6 @@ def color_brewer(color_code, n=6):
     return color_scheme
 
 
-def split_six(series=None):
-    """
-    Given a Pandas Series, get a domain of values from zero to the 90% quantile
-    rounded to the nearest order-of-magnitude integer. For example, 2100 is
-    rounded to 2000, 2790 to 3000.
-
-    Parameters
-    ----------
-    series: Pandas series, default None
-
-    Returns
-    -------
-    list
-
-    """
-    if pd is None:
-        raise ImportError("The Pandas package is required" " for this functionality")
-    if np is None:
-        raise ImportError("The NumPy package is required" " for this functionality")
-
-    def base(x):
-        if x > 0:
-            base = pow(10, math.floor(math.log10(x)))
-            return round(x / base) * base
-        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]
-
-
 def image_to_url(image, colormap=None, origin="upper"):
     """Infers the type of an image argument and transforms it into a URL.