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De-duplicate masking/fallback logic in ops #19613

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Feb 13, 2018
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12 changes: 1 addition & 11 deletions pandas/core/frame.py
Original file line number Diff line number Diff line change
Expand Up @@ -3920,17 +3920,7 @@ def _combine_frame(self, other, func, fill_value=None, level=None):
new_index, new_columns = this.index, this.columns

def _arith_op(left, right):
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you might be able to simplify this even more here (IOW remove _arith_op) and just in-line it

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This overlaps with #19611. This will probably get in before that does, so I'll take a look at this suggestion after rebasing there.

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aok

if fill_value is not None:
left_mask = isna(left)
right_mask = isna(right)
left = left.copy()
right = right.copy()

# one but not both
mask = left_mask ^ right_mask
left[left_mask & mask] = fill_value
right[right_mask & mask] = fill_value

left, right = ops.fill_binop(left, right, fill_value)
return func(left, right)

if this._is_mixed_type or other._is_mixed_type:
Expand Down
163 changes: 83 additions & 80 deletions pandas/core/ops.py
Original file line number Diff line number Diff line change
Expand Up @@ -398,6 +398,85 @@ def _make_flex_doc(op_name, typ):
return doc


# -----------------------------------------------------------------------------
# Masking NA values and fallbacks for operations numpy does not support

def fill_binop(left, right, fill_value):
if fill_value is not None:
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can you add a doc-string

left_mask = isna(left)
right_mask = isna(right)
left = left.copy()
right = right.copy()

# one but not both
mask = left_mask ^ right_mask
left[left_mask & mask] = fill_value
right[right_mask & mask] = fill_value
return left, right


def mask_arith_op(x, y, op):
xrav = x.ravel()
if isinstance(y, (np.ndarray, ABCSeries, pd.Index)):
# The ABCSeries and pd.Index cases are only reached for Series ops,
# DataFrame casts these inputs to Series in align_method_FRAME
dtype = find_common_type([x.dtype, y.dtype])
result = np.empty(x.size, dtype=dtype)
yrav = y.ravel()
mask = notna(xrav) & notna(yrav)
xrav = xrav[mask]

if yrav.shape != mask.shape:
# Only a risk for DataFrame.
# FIXME: GH#5284, GH#5035, GH#19448
# Without specifically raising here we get mismatched
# errors in Py3 (TypeError) vs Py2 (ValueError)
raise ValueError('Cannot broadcast operands together.')

yrav = com._values_from_object(y[mask])
if xrav.size:
# Avoid the operation if it is on an empty array
with np.errstate(all='ignore'):
result[mask] = op(xrav, yrav)

elif isinstance(x, np.ndarray):
# this always holds for Series, never for DataFrame
result = np.empty(x.size, dtype=x.dtype)
mask = notna(x)
result[mask] = op(x[mask], y)

else:
# Raise otherwise; only relevant for DataFrame
raise TypeError("cannot perform operation {op} between "
"objects of type {x} and {y}".format(op=name,
x=type(x),
y=type(y)))

result, changed = maybe_upcast_putmask(result, ~mask, np.nan)
return result.reshape(x.shape)


def mask_cmp_op(x, y, op, allowed_types):
# TODO: Can we make the allowed_types arg unnecessary?
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can you add a doc-string

xrav = x.ravel()
result = np.empty(x.size, dtype=bool)
if isinstance(y, allowed_types):
yrav = y.ravel()
mask = notna(xrav) & notna(yrav)
result[mask] = op(np.array(list(xrav[mask])),
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Do you know why we build the intermediate list here?

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No idea. I can try removing it and see if that affects any tests.

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Looks like a complex-dtype test would be affected.

np.array(list(yrav[mask])))
else:
mask = notna(xrav)
result[mask] = op(np.array(list(xrav[mask])), y)

if op == operator.ne: # pragma: no cover
np.putmask(result, ~mask, True)
else:
np.putmask(result, ~mask, False)
result = result.reshape(x.shape)
return result


# -----------------------------------------------------------------------------
# Functions that add arithmetic methods to objects, given arithmetic factory
# methods
Expand Down Expand Up @@ -642,18 +721,7 @@ def na_op(x, y):
try:
result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
except TypeError:
if isinstance(y, (np.ndarray, ABCSeries, pd.Index)):
dtype = find_common_type([x.dtype, y.dtype])
result = np.empty(x.size, dtype=dtype)
mask = notna(x) & notna(y)
result[mask] = op(x[mask], com._values_from_object(y[mask]))
else:
assert isinstance(x, np.ndarray)
result = np.empty(len(x), dtype=x.dtype)
mask = notna(x)
result[mask] = op(x[mask], y)

result, changed = maybe_upcast_putmask(result, ~mask, np.nan)
result = mask_arith_op(x, y, op)

result = missing.fill_zeros(result, x, y, name, fill_zeros)
return result
Expand Down Expand Up @@ -1053,40 +1121,7 @@ def na_op(x, y):
try:
result = expressions.evaluate(op, str_rep, x, y, **eval_kwargs)
except TypeError:
xrav = x.ravel()
if isinstance(y, (np.ndarray, ABCSeries)):
dtype = np.find_common_type([x.dtype, y.dtype], [])
result = np.empty(x.size, dtype=dtype)
yrav = y.ravel()
mask = notna(xrav) & notna(yrav)
xrav = xrav[mask]

if yrav.shape != mask.shape:
# FIXME: GH#5284, GH#5035, GH#19448
# Without specifically raising here we get mismatched
# errors in Py3 (TypeError) vs Py2 (ValueError)
raise ValueError('Cannot broadcast operands together.')

yrav = yrav[mask]
if xrav.size:
with np.errstate(all='ignore'):
result[mask] = op(xrav, yrav)

elif isinstance(x, np.ndarray):
# mask is only meaningful for x
result = np.empty(x.size, dtype=x.dtype)
mask = notna(xrav)
xrav = xrav[mask]
if xrav.size:
with np.errstate(all='ignore'):
result[mask] = op(xrav, y)
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I don't think this case is reached/reachable. If y is an ndarray then most non-trivial cases should have shape mismatches if this were ever reached.

else:
raise TypeError("cannot perform operation {op} between "
"objects of type {x} and {y}".format(
op=name, x=type(x), y=type(y)))

result, changed = maybe_upcast_putmask(result, ~mask, np.nan)
result = result.reshape(x.shape)
result = mask_arith_op(x, y, op)

result = missing.fill_zeros(result, x, y, name, fill_zeros)

Expand Down Expand Up @@ -1127,23 +1162,7 @@ def na_op(x, y):
with np.errstate(invalid='ignore'):
result = op(x, y)
except TypeError:
xrav = x.ravel()
result = np.empty(x.size, dtype=bool)
if isinstance(y, (np.ndarray, ABCSeries)):
yrav = y.ravel()
mask = notna(xrav) & notna(yrav)
result[mask] = op(np.array(list(xrav[mask])),
np.array(list(yrav[mask])))
else:
mask = notna(xrav)
result[mask] = op(np.array(list(xrav[mask])), y)

if op == operator.ne: # pragma: no cover
np.putmask(result, ~mask, True)
else:
np.putmask(result, ~mask, False)
result = result.reshape(x.shape)

result = mask_cmp_op(x, y, op, (np.ndarray, ABCSeries))
return result

@Appender('Wrapper for flexible comparison methods {name}'
Expand Down Expand Up @@ -1221,23 +1240,7 @@ def na_op(x, y):
try:
result = expressions.evaluate(op, str_rep, x, y)
except TypeError:
xrav = x.ravel()
result = np.empty(x.size, dtype=bool)
if isinstance(y, np.ndarray):
yrav = y.ravel()
mask = notna(xrav) & notna(yrav)
result[mask] = op(np.array(list(xrav[mask])),
np.array(list(yrav[mask])))
else:
mask = notna(xrav)
result[mask] = op(np.array(list(xrav[mask])), y)

if op == operator.ne: # pragma: no cover
np.putmask(result, ~mask, True)
else:
np.putmask(result, ~mask, False)
result = result.reshape(x.shape)

result = mask_cmp_op(x, y, op, np.ndarray)
return result

@Appender('Wrapper for comparison method {name}'.format(name=name))
Expand Down
15 changes: 2 additions & 13 deletions pandas/core/series.py
Original file line number Diff line number Diff line change
Expand Up @@ -1725,19 +1725,8 @@ def _binop(self, other, func, level=None, fill_value=None):
copy=False)
new_index = this.index

this_vals = this.values
other_vals = other.values

if fill_value is not None:
this_mask = isna(this_vals)
other_mask = isna(other_vals)
this_vals = this_vals.copy()
other_vals = other_vals.copy()

# one but not both
mask = this_mask ^ other_mask
this_vals[this_mask & mask] = fill_value
other_vals[other_mask & mask] = fill_value
this_vals, other_vals = ops.fill_binop(this.values, other.values,
fill_value)

with np.errstate(all='ignore'):
result = func(this_vals, other_vals)
Expand Down