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from agate.computations.base import Computation
class Formula(Computation):
"""
Apply an arbitrary function to each row.
:param data_type:
The data type this formula will return.
:param func:
The function to be applied to each row. Must return a valid value for
the specified data type.
:param cast:
If :code:`True`, each return value will be cast to the specified
:code:`data_type` to ensure it is valid. Only disable this if you are
certain your formula always returns the correct type.
"""
def __init__(self, data_type, func, cast=True):
self._data_type = data_type
self._func = func
self._cast = cast
def get_computed_data_type(self, table):
return self._data_type
def run(self, table):
new_column = []
for row in table.rows:
v = self._func(row)
if self._cast:
v = self._data_type.cast(v)
new_column.append(v)
return new_column
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