takes from LEFT where criteria is True else RIGHT
and creates a single new column.
:param: T: Table
:param: criteria: np.array(bool):
if True take left column
else take right column
:param left: (str) column name
:param right: (str) column name
:param new: (str) new name
:returns: T
Source code in tablite/merge.py
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50 | def where(T, criteria, left, right, new):
""" takes from LEFT where criteria is True else RIGHT
and creates a single new column.
:param: T: Table
:param: criteria: np.array(bool):
if True take left column
else take right column
:param left: (str) column name
:param right: (str) column name
:param new: (str) new name
:returns: T
"""
type_check(T, BaseTable)
if isinstance(criteria, np.ndarray):
if not criteria.dtype == "bool":
raise TypeError
else:
criteria = np.array(criteria, dtype='bool')
new_uq = unique_name(new, list(T.columns))
T.add_column(new_uq)
col = T[new_uq]
for start,end in Config.page_steps(len(criteria)):
left_values = T[left][start:end]
right_values = T[right][start:end]
new_values = np.where(criteria, left_values, right_values)
col.extend(new_values)
if new == right:
T[right] = T[new_uq] # keep column order
del T[new_uq]
del T[left]
elif new == left:
T[left] = T[new_uq] # keep column order
del T[new_uq]
del T[right]
else:
T[new] = T[new_uq]
del T[left]
del T[right]
return T
|