def _round(x, y):
# Python 3 uses "banker's rounding": when a value is equidistant between
# two rounded numbers, it rounds to the even digit. For example
# >>> round(2.5)
# 2
# >>> round(3.5)
# 4
# >>> round(2.25, 2)
# 2.2
#
# So, I've reimplemented the rounding most people expect.
#
# Either way, imprecision effects come into play. With either rounding,
# one would expect round(2.675, 2) to be 2.68, but 2.675 is stored as
# something slightly smaller than 2.675, so it rounds down to 2.67.
#
# Stata has this latter issue as well, depending on use. If you use
# round(2.675, 0.01) interactively, you'll get 2.68. If you use
# round(x, 0.01) where x is a variable containing 2.675 (approx), then
# you get 2.67. If you use round(x, y) where x is a variable containing
# 2.675 (approx) and y is a variable containing 0.01 (approx), then you
# get 2.68 (approx).
#
# . di round(2.675, 0.01)
# 2.68
#
# . clear
#
# . set obs 1
# obs was 0, now 1
#
# . gen x = 2.675
#
# . di round(x, 0.01)
# 2.67
#
# . clear
#
# . set obs 1
# obs was 0, now 1
#
# . gen x = 2.675
#
# . gen y = 0.01
#
# . di round(x, y)
# 2.6799999
#
if _is_missing(y):
return mv
if y == 0:
if _is_missing(x) and not isinstance(x, MissingValue):
return get_missing(x)
return x
if _is_missing(x):
return x if isinstance(x, MissingValue) else get_missing(x)
return math.floor(x / y + 0.5) * y
def _round(x, y):
# Python 3 uses "banker's rounding": when a value is equidistant between
# two rounded numbers, it rounds to the even digit. For example
# >>> round(2.5)
# 2
# >>> round(3.5)
# 4
# >>> round(2.25, 2)
# 2.2
#
# So, I've reimplemented the rounding most people expect.
#
# Either way, imprecision effects come into play. With either rounding,
# one would expect round(2.675, 2) to be 2.68, but 2.675 is stored as
# something slightly smaller than 2.675, so it rounds down to 2.67.
#
# Stata has this latter issue as well, depending on use. If you use
# round(2.675, 0.01) interactively, you'll get 2.68. If you use
# round(x, 0.01) where x is a variable containing 2.675 (approx), then
# you get 2.67. If you use round(x, y) where x is a variable containing
# 2.675 (approx) and y is a variable containing 0.01 (approx), then you
# get 2.68 (approx).
#
# . di round(2.675, 0.01)
# 2.68
#
# . clear
#
# . set obs 1
# obs was 0, now 1
#
# . gen x = 2.675
#
# . di round(x, 0.01)
# 2.67
#
# . clear
#
# . set obs 1
# obs was 0, now 1
#
# . gen x = 2.675
#
# . gen y = 0.01
#
# . di round(x, y)
# 2.6799999
#
if _is_missing(y):
return mv
if y == 0:
if _is_missing(x) and not isinstance(x, MissingValue):
return get_missing(x)
return x
if _is_missing(x):
return x if isinstance(x, MissingValue) else get_missing(x)
return math.floor(x / y + 0.5) * y
def _reldif(x, y):
missing = False
if x is None or (not isinstance(x, MissingValue) and
(x < -8.988465674311579e+307 or x > 8.988465674311579e+307)):
x = get_missing(x)
missing = True
if y is None or (not isinstance(y, MissingValue) and
(y < -8.988465674311579e+307 or y > 8.988465674311579e+307)):
y = get_missing(y)
missing = True
if x == y:
return 0
if missing:
return mv
return abs(x - y) / (abs(y) + 1)
def _reldif(x, y):
missing = False
if x is None or (not isinstance(x, MissingValue) and
(x < -8.988465674311579e+307
or x > 8.988465674311579e+307)):
x = get_missing(x)
missing = True
if y is None or (not isinstance(y, MissingValue) and
(y < -8.988465674311579e+307
or y > 8.988465674311579e+307)):
y = get_missing(y)
missing = True
if x == y:
return 0
if missing:
return mv
return abs(x - y) / (abs(y) + 1)
def _int(x):
if isinstance(x, MissingValue):
return x
if x is None:
return mv
if not isinstance(x, int) and not isinstance(x, float):
raise TypeError("int, float, or MissingValue instance required")
if not -8.988465674311579e+307 <= x <= 8.988465674311579e+307:
return get_missing(x)
return int(x)
def _int(x):
if isinstance(x, MissingValue):
return x
if x is None:
return mv
if not isinstance(x, int) and not isinstance(x, float):
raise TypeError("int, float, or MissingValue instance required")
if not -8.988465674311579e+307 <= x <= 8.988465674311579e+307:
return get_missing(x)
return int(x)
def st_round(x, y=1):
"""Rounding function.
Parameters
----------
x : float, int, MissingValue instance, or None
y : float, int, MissingValue instance, or None;
y is optional, default value is 1
Returns
-------
If both x and y are non-missing, returns x / y rounded to
the nearest integer times y (but see notes below).
If y is 1 or y is not specified, returns x rounded to the
nearest integer (but see notes below).
If y is zero, returns x.
If y is missing, MISSING (".") is returned.
If x is missing and y is non-missing, returns MissingValue
corresponding to x.
If both x and y are missing, returns MISSING (".").
Notes
-----
Though Python 3 uses "banker's rounding" or "round half to even",
this function uses "round half up". For example, with Python 3's
`round` function, `round(3.5)` and `round(4.5)` are both 4, but
`st_round(3.5)` is 4 and `st_round(4.5)` is 5.
Keep in mind that floating point imprecision of inputs may affect
the output.
"""
if isinstance(x, StataVarVals):
if isinstance(y, StataVarVals):
return StataVarVals([
_round(vx, vy) for vx, vy in zip(x.values, y.values)
])
if y == 0:
return StataVarVals([
get_missing(v)
if _is_missing(v) and not isinstance(v, MissingValue)
else v for v in x.values
])
else:
return StataVarVals([
_round(v, y) for v in x.values
])
if isinstance(y, StataVarVals):
return StataVarVals([
_round(x, v) for v in y.values
])
return _round(x, y)
def st_round(x, y=1):
"""Rounding function.
Parameters
----------
x : float, int, MissingValue instance, or None
y : float, int, MissingValue instance, or None;
y is optional, default value is 1
Returns
-------
If both x and y are non-missing, returns x / y rounded to
the nearest integer times y (but see notes below).
If y is 1 or y is not specified, returns x rounded to the
nearest integer (but see notes below).
If y is zero, returns x.
If y is missing, MISSING (".") is returned.
If x is missing and y is non-missing, returns MissingValue
corresponding to x.
If both x and y are missing, returns MISSING (".").
Notes
-----
Though Python 3 uses "banker's rounding" or "round half to even",
this function uses "round half up". For example, with Python 3's
`round` function, `round(3.5)` and `round(4.5)` are both 4, but
`st_round(3.5)` is 4 and `st_round(4.5)` is 5.
Keep in mind that floating point imprecision of inputs may affect
the output.
"""
if isinstance(x, StataVarVals):
if isinstance(y, StataVarVals):
return StataVarVals(
[_round(vx, vy) for vx, vy in zip(x.values, y.values)])
if y == 0:
return StataVarVals([
get_missing(v)
if _is_missing(v) and not isinstance(v, MissingValue) else v
for v in x.values
])
else:
return StataVarVals([_round(v, y) for v in x.values])
if isinstance(y, StataVarVals):
return StataVarVals([_round(x, v) for v in y.values])
return _round(x, y)
