141 lines
4.4 KiB
Python
141 lines
4.4 KiB
Python
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#!/usr/bin/env python
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from datetime import date, datetime
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import six
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from leather.data_types import Date, DateTime, Number, Text
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from leather.shapes import Bars, Columns
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class Scale(object):
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"""
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Base class for various kinds of scale objects.
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"""
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@classmethod
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def infer(cls, layers, dimension, data_type):
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"""
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Infer's an appropriate default scale for a given sequence of
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:class:`.Series`.
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:param chart_series:
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A sequence of :class:`.Series` instances
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:param dimension:
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The dimension, :code:`X` or :code:`Y` of the data to infer for.
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:param data_type:
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The type of data contained in the series dimension.
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"""
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from leather.scales.linear import Linear
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from leather.scales.ordinal import Ordinal
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from leather.scales.temporal import Temporal
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# Default Time scale is Temporal
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if data_type is Date:
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data_min = date.max
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data_max = date.min
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for series, shape in layers:
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data_min = min(data_min, series.min(dimension))
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data_max = max(data_max, series.max(dimension))
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scale = Temporal(data_min, data_max)
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elif data_type is DateTime:
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data_min = datetime.max
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data_max = datetime.min
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for series, shape in layers:
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data_min = min(data_min, series.min(dimension))
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data_max = max(data_max, series.max(dimension))
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scale = Temporal(data_min, data_max)
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# Default Number scale is Linear
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elif data_type is Number:
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force_zero = False
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data_min = None
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data_max = None
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for series, shape in layers:
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if isinstance(shape, (Bars, Columns)):
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force_zero = True
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if data_min is None:
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data_min = series.min(dimension)
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else:
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data_min = min(data_min, series.min(dimension))
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if data_max is None:
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data_max = series.max(dimension)
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else:
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data_max = max(data_max, series.max(dimension))
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if force_zero:
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if data_min > 0:
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data_min = 0
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if data_max < 0:
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data_max = 0
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scale = Linear(data_min, data_max)
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# Default Text scale is Ordinal
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elif data_type is Text:
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scale_values = None
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# First case: a single set of ordinal labels
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if len(layers) == 1:
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scale_values = layers[0][0].values(dimension)
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else:
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first_series = set(layers[0][0].values(dimension))
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data_series = [series.values(dimension) for series, shape in layers]
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all_same = True
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for series in data_series:
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if set(series) != first_series:
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all_same = False
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break
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# Second case: multiple identical sets of ordinal labels
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if all_same:
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scale_values = layers[0][0].values(dimension)
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# Third case: multiple different sets of ordinal labels
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else:
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scale_values = sorted(list(set().union(*data_series)))
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scale = Ordinal(scale_values)
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return scale
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def contains(self, v):
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"""
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Return :code:`True` if a given value is contained within this scale's
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displayed domain.
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"""
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raise NotImplementedError
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def project(self, value, range_min, range_max):
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"""
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Project a value in this scale's domain to a target range.
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"""
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raise NotImplementedError
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def project_interval(self, value, range_min, range_max):
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"""
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Project a value in this scale's domain to an interval in the target
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range. This is used for places :class:`.Bars` and :class:`.Columns`.
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"""
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raise NotImplementedError
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def ticks(self):
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"""
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Generate a series of ticks for this scale.
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"""
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raise NotImplementedError
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def format_tick(self, value, i, count):
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"""
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Format ticks for display.
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This method is used as a default which will be ignored if the user
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provides a custom tick formatter to the axis.
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"""
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return six.text_type(value)
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