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from decimal import Decimal
from babel.numbers import format_decimal
from agate import utils
from agate.aggregations import Max, Min
def bins(self, column_name, count=10, start=None, end=None):
"""
Generates (approximately) evenly sized bins for the values in a column.
Bins may not be perfectly even if the spread of the data does not divide
evenly, but all values will always be included in some bin.
The resulting table will have two columns. The first will have
the same name as the specified column, but will be type :class:`.Text`.
The second will be named :code:`count` and will be of type
:class:`.Number`.
:param column_name:
The name of the column to bin. Must be of type :class:`.Number`
:param count:
The number of bins to create. If not specified then each value will
be counted as its own bin.
:param start:
The minimum value to start the bins at. If not specified the
minimum value in the column will be used.
:param end:
The maximum value to end the bins at. If not specified the maximum
value in the column will be used.
:returns:
A new :class:`Table`.
"""
minimum, maximum = utils.round_limits(
Min(column_name).run(self),
Max(column_name).run(self)
)
# Infer bin start/end positions
start = minimum if not start else Decimal(start)
end = maximum if not end else Decimal(end)
# Calculate bin size
spread = abs(end - start)
size = spread / count
breaks = [start]
# Calculate breakpoints
for i in range(1, count + 1):
top = start + (size * i)
breaks.append(top)
# Format bin names
decimal_places = utils.max_precision(breaks)
break_formatter = utils.make_number_formatter(decimal_places)
def name_bin(i, j, first_exclusive=True, last_exclusive=False):
inclusive = format_decimal(i, format=break_formatter)
exclusive = format_decimal(j, format=break_formatter)
output = '[' if first_exclusive else '('
output += f'{inclusive} - {exclusive}'
output += ']' if last_exclusive else ')'
return output
# Generate bins
bin_names = []
for i in range(1, len(breaks)):
last_exclusive = (i == len(breaks) - 1)
if i == 1 and minimum < start:
name = name_bin(minimum, breaks[i], last_exclusive=last_exclusive)
elif i == len(breaks) - 1 and maximum > end:
name = name_bin(breaks[i - 1], maximum, last_exclusive=last_exclusive)
else:
name = name_bin(breaks[i - 1], breaks[i], last_exclusive=last_exclusive)
bin_names.append(name)
bin_names.append(None)
# Lambda method for actually assigning values to bins
def binner(row):
value = row[column_name]
if value is None:
return None
i = 1
try:
while value >= breaks[i]:
i += 1
except IndexError:
i -= 1
return bin_names[i - 1]
# Pivot by lambda
table = self.pivot(binner, key_name=column_name)
# Sort by bin order
return table.order_by(lambda r: bin_names.index(r[column_name]))
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