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"""Automatically adapted for numpy Sep 19, 2005 by convertcode.py
"""
from __future__ import division, absolute_import, print_function
__all__ = ['iscomplexobj', 'isrealobj', 'imag', 'iscomplex',
'isreal', 'nan_to_num', 'real', 'real_if_close',
'typename', 'asfarray', 'mintypecode', 'asscalar',
'common_type']
import numpy.core.numeric as _nx
from numpy.core.numeric import asarray, asanyarray, array, isnan, \
obj2sctype, zeros
from .ufunclike import isneginf, isposinf
_typecodes_by_elsize = 'GDFgdfQqLlIiHhBb?'
def mintypecode(typechars,typeset='GDFgdf',default='d'):
"""
Return the character for the minimum-size type to which given types can
be safely cast.
The returned type character must represent the smallest size dtype such
that an array of the returned type can handle the data from an array of
all types in `typechars` (or if `typechars` is an array, then its
dtype.char).
Parameters
----------
typechars : list of str or array_like
If a list of strings, each string should represent a dtype.
If array_like, the character representation of the array dtype is used.
typeset : str or list of str, optional
The set of characters that the returned character is chosen from.
The default set is 'GDFgdf'.
default : str, optional
The default character, this is returned if none of the characters in
`typechars` matches a character in `typeset`.
Returns
-------
typechar : str
The character representing the minimum-size type that was found.
See Also
--------
dtype, sctype2char, maximum_sctype
Examples
--------
>>> np.mintypecode(['d', 'f', 'S'])
'd'
>>> x = np.array([1.1, 2-3.j])
>>> np.mintypecode(x)
'D'
>>> np.mintypecode('abceh', default='G')
'G'
"""
typecodes = [(isinstance(t, str) and t) or asarray(t).dtype.char\
for t in typechars]
intersection = [t for t in typecodes if t in typeset]
if not intersection:
return default
if 'F' in intersection and 'd' in intersection:
return 'D'
l = []
for t in intersection:
i = _typecodes_by_elsize.index(t)
l.append((i, t))
l.sort()
return l[0][1]
def asfarray(a, dtype=_nx.float_):
"""
Return an array converted to a float type.
Parameters
----------
a : array_like
The input array.
dtype : str or dtype object, optional
Float type code to coerce input array `a`. If `dtype` is one of the
'int' dtypes, it is replaced with float64.
Returns
-------
out : ndarray
The input `a` as a float ndarray.
Examples
--------
>>> np.asfarray([2, 3])
array([ 2., 3.])
>>> np.asfarray([2, 3], dtype='float')
array([ 2., 3.])
>>> np.asfarray([2, 3], dtype='int8')
array([ 2., 3.])
"""
dtype = _nx.obj2sctype(dtype)
if not issubclass(dtype, _nx.inexact):
dtype = _nx.float_
return asarray(a, dtype=dtype)
def real(val):
"""
Return the real part of the elements of the array.
Parameters
----------
val : array_like
Input array.
Returns
-------
out : ndarray
Output array. If `val` is real, the type of `val` is used for the
output. If `val` has complex elements, the returned type is float.
See Also
--------
real_if_close, imag, angle
Examples
--------
>>> a = np.array([1+2j, 3+4j, 5+6j])
>>> a.real
array([ 1., 3., 5.])
>>> a.real = 9
>>> a
array([ 9.+2.j, 9.+4.j, 9.+6.j])
>>> a.real = np.array([9, 8, 7])
>>> a
array([ 9.+2.j, 8.+4.j, 7.+6.j])
"""
return asanyarray(val).real
def imag(val):
"""
Return the imaginary part of the elements of the array.
Parameters
----------
val : array_like
Input array.
Returns
-------
out : ndarray
Output array. If `val` is real, the type of `val` is used for the
output. If `val` has complex elements, the returned type is float.
See Also
--------
real, angle, real_if_close
Examples
--------
>>> a = np.array([1+2j, 3+4j, 5+6j])
>>> a.imag
array([ 2., 4., 6.])
>>> a.imag = np.array([8, 10, 12])
>>> a
array([ 1. +8.j, 3.+10.j, 5.+12.j])
"""
return asanyarray(val).imag
def iscomplex(x):
"""
Returns a bool array, where True if input element is complex.
What is tested is whether the input has a non-zero imaginary part, not if
the input type is complex.
Parameters
----------
x : array_like
Input array.
Returns
-------
out : ndarray of bools
Output array.
See Also
--------
isreal
iscomplexobj : Return True if x is a complex type or an array of complex
numbers.
Examples
--------
>>> np.iscomplex([1+1j, 1+0j, 4.5, 3, 2, 2j])
array([ True, False, False, False, False, True], dtype=bool)
"""
ax = asanyarray(x)
if issubclass(ax.dtype.type, _nx.complexfloating):
return ax.imag != 0
res = zeros(ax.shape, bool)
return +res # convet to array-scalar if needed
def isreal(x):
"""
Returns a bool array, where True if input element is real.
If element has complex type with zero complex part, the return value
for that element is True.
Parameters
----------
x : array_like
Input array.
Returns
-------
out : ndarray, bool
Boolean array of same shape as `x`.
See Also
--------
iscomplex
isrealobj : Return True if x is not a complex type.
Examples
--------
>>> np.isreal([1+1j, 1+0j, 4.5, 3, 2, 2j])
array([False, True, True, True, True, False], dtype=bool)
"""
return imag(x) == 0
def iscomplexobj(x):
"""
Check for a complex type or an array of complex numbers.
The type of the input is checked, not the value. Even if the input
has an imaginary part equal to zero, `iscomplexobj` evaluates to True.
Parameters
----------
x : any
The input can be of any type and shape.
Returns
-------
iscomplexobj : bool
The return value, True if `x` is of a complex type or has at least
one complex element.
See Also
--------
isrealobj, iscomplex
Examples
--------
>>> np.iscomplexobj(1)
False
>>> np.iscomplexobj(1+0j)
True
>>> np.iscomplexobj([3, 1+0j, True])
True
"""
return issubclass( asarray(x).dtype.type, _nx.complexfloating)
def isrealobj(x):
"""
Return True if x is a not complex type or an array of complex numbers.
The type of the input is checked, not the value. So even if the input
has an imaginary part equal to zero, `isrealobj` evaluates to False
if the data type is complex.
Parameters
----------
x : any
The input can be of any type and shape.
Returns
-------
y : bool
The return value, False if `x` is of a complex type.
See Also
--------
iscomplexobj, isreal
Examples
--------
>>> np.isrealobj(1)
True
>>> np.isrealobj(1+0j)
False
>>> np.isrealobj([3, 1+0j, True])
False
"""
return not issubclass( asarray(x).dtype.type, _nx.complexfloating)
#-----------------------------------------------------------------------------
def _getmaxmin(t):
from numpy.core import getlimits
f = getlimits.finfo(t)
return f.max, f.min
def nan_to_num(x):
"""
Replace nan with zero and inf with finite numbers.
Returns an array or scalar replacing Not a Number (NaN) with zero,
(positive) infinity with a very large number and negative infinity
with a very small (or negative) number.
Parameters
----------
x : array_like
Input data.
Returns
-------
out : ndarray, float
Array with the same shape as `x` and dtype of the element in `x` with
the greatest precision. NaN is replaced by zero, and infinity
(-infinity) is replaced by the largest (smallest or most negative)
floating point value that fits in the output dtype. All finite numbers
are upcast to the output dtype (default float64).
See Also
--------
isinf : Shows which elements are negative or negative infinity.
isneginf : Shows which elements are negative infinity.
isposinf : Shows which elements are positive infinity.
isnan : Shows which elements are Not a Number (NaN).
isfinite : Shows which elements are finite (not NaN, not infinity)
Notes
-----
Numpy uses the IEEE Standard for Binary Floating-Point for Arithmetic
(IEEE 754). This means that Not a Number is not equivalent to infinity.
Examples
--------
>>> np.set_printoptions(precision=8)
>>> x = np.array([np.inf, -np.inf, np.nan, -128, 128])
>>> np.nan_to_num(x)
array([ 1.79769313e+308, -1.79769313e+308, 0.00000000e+000,
-1.28000000e+002, 1.28000000e+002])
"""
try:
t = x.dtype.type
except AttributeError:
t = obj2sctype(type(x))
if issubclass(t, _nx.complexfloating):
return nan_to_num(x.real) + 1j * nan_to_num(x.imag)
else:
try:
y = x.copy()
except AttributeError:
y = array(x)
if not issubclass(t, _nx.integer):
if not y.shape:
y = array([x])
scalar = True
else:
scalar = False
are_inf = isposinf(y)
are_neg_inf = isneginf(y)
are_nan = isnan(y)
maxf, minf = _getmaxmin(y.dtype.type)
y[are_nan] = 0
y[are_inf] = maxf
y[are_neg_inf] = minf
if scalar:
y = y[0]
return y
#-----------------------------------------------------------------------------
def real_if_close(a,tol=100):
"""
If complex input returns a real array if complex parts are close to zero.
"Close to zero" is defined as `tol` * (machine epsilon of the type for
`a`).
Parameters
----------
a : array_like
Input array.
tol : float
Tolerance in machine epsilons for the complex part of the elements
in the array.
Returns
-------
out : ndarray
If `a` is real, the type of `a` is used for the output. If `a`
has complex elements, the returned type is float.
See Also
--------
real, imag, angle
Notes
-----
Machine epsilon varies from machine to machine and between data types
but Python floats on most platforms have a machine epsilon equal to
2.2204460492503131e-16. You can use 'np.finfo(np.float).eps' to print
out the machine epsilon for floats.
Examples
--------
>>> np.finfo(np.float).eps
2.2204460492503131e-16
>>> np.real_if_close([2.1 + 4e-14j], tol=1000)
array([ 2.1])
>>> np.real_if_close([2.1 + 4e-13j], tol=1000)
array([ 2.1 +4.00000000e-13j])
"""
a = asanyarray(a)
if not issubclass(a.dtype.type, _nx.complexfloating):
return a
if tol > 1:
from numpy.core import getlimits
f = getlimits.finfo(a.dtype.type)
tol = f.eps * tol
if _nx.allclose(a.imag, 0, atol=tol):
a = a.real
return a
def asscalar(a):
"""
Convert an array of size 1 to its scalar equivalent.
Parameters
----------
a : ndarray
Input array of size 1.
Returns
-------
out : scalar
Scalar representation of `a`. The output data type is the same type
returned by the input's `item` method.
Examples
--------
>>> np.asscalar(np.array([24]))
24
"""
return a.item()
#-----------------------------------------------------------------------------
_namefromtype = {'S1' : 'character',
'?' : 'bool',
'b' : 'signed char',
'B' : 'unsigned char',
'h' : 'short',
'H' : 'unsigned short',
'i' : 'integer',
'I' : 'unsigned integer',
'l' : 'long integer',
'L' : 'unsigned long integer',
'q' : 'long long integer',
'Q' : 'unsigned long long integer',
'f' : 'single precision',
'd' : 'double precision',
'g' : 'long precision',
'F' : 'complex single precision',
'D' : 'complex double precision',
'G' : 'complex long double precision',
'S' : 'string',
'U' : 'unicode',
'V' : 'void',
'O' : 'object'
}
def typename(char):
"""
Return a description for the given data type code.
Parameters
----------
char : str
Data type code.
Returns
-------
out : str
Description of the input data type code.
See Also
--------
dtype, typecodes
Examples
--------
>>> typechars = ['S1', '?', 'B', 'D', 'G', 'F', 'I', 'H', 'L', 'O', 'Q',
... 'S', 'U', 'V', 'b', 'd', 'g', 'f', 'i', 'h', 'l', 'q']
>>> for typechar in typechars:
... print typechar, ' : ', np.typename(typechar)
...
S1 : character
? : bool
B : unsigned char
D : complex double precision
G : complex long double precision
F : complex single precision
I : unsigned integer
H : unsigned short
L : unsigned long integer
O : object
Q : unsigned long long integer
S : string
U : unicode
V : void
b : signed char
d : double precision
g : long precision
f : single precision
i : integer
h : short
l : long integer
q : long long integer
"""
return _namefromtype[char]
#-----------------------------------------------------------------------------
#determine the "minimum common type" for a group of arrays.
array_type = [[_nx.single, _nx.double, _nx.longdouble],
[_nx.csingle, _nx.cdouble, _nx.clongdouble]]
array_precision = {_nx.single : 0,
_nx.double : 1,
_nx.longdouble : 2,
_nx.csingle : 0,
_nx.cdouble : 1,
_nx.clongdouble : 2}
def common_type(*arrays):
"""
Return a scalar type which is common to the input arrays.
The return type will always be an inexact (i.e. floating point) scalar
type, even if all the arrays are integer arrays. If one of the inputs is
an integer array, the minimum precision type that is returned is a
64-bit floating point dtype.
All input arrays can be safely cast to the returned dtype without loss
of information.
Parameters
----------
array1, array2, ... : ndarrays
Input arrays.
Returns
-------
out : data type code
Data type code.
See Also
--------
dtype, mintypecode
Examples
--------
>>> np.common_type(np.arange(2, dtype=np.float32))
<type 'numpy.float32'>
>>> np.common_type(np.arange(2, dtype=np.float32), np.arange(2))
<type 'numpy.float64'>
>>> np.common_type(np.arange(4), np.array([45, 6.j]), np.array([45.0]))
<type 'numpy.complex128'>
"""
is_complex = False
precision = 0
for a in arrays:
t = a.dtype.type
if iscomplexobj(a):
is_complex = True
if issubclass(t, _nx.integer):
p = 1
else:
p = array_precision.get(t, None)
if p is None:
raise TypeError("can't get common type for non-numeric array")
precision = max(precision, p)
if is_complex:
return array_type[1][precision]
else:
return array_type[0][precision]
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