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ENH: allow use of custom formatter in array2string. Closes #1218. #72

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09a6cc1
ENH: allow use of custom formatter in array2string. Closes #1218.
Apr 3, 2011
8a1b057
ENH: allow setting a custom array element formatter in set_printoptions.
Apr 17, 2011
fe4b115
ENH: change formatter keyword in array2string to a dict.
Apr 20, 2011
0ab99a0
DOC: fix set_printoptions docstring after change to formatter kw.
Apr 22, 2011
ad9d161
TST: finish test for custom formatter for string arrays.
Apr 22, 2011
c32bc22
STY: some code and docstring changes for readability/consistency.
Apr 24, 2011
41a2b7c
STY: apply docstring improvement also to set_printoptions.
Apr 24, 2011
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12 changes: 12 additions & 0 deletions doc/release/2.0.0-notes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,19 @@ Highlights
New features
============

Custom formatter for printing arrays
------------------------------------



Changes
=======



Deprecations
============

Specifying a custom string formatter with a `_format` array attribute is
deprecated. The new `formatter` keyword in ``numpy.set_printoptions`` or
``numpy.array2string`` can be used instead.
217 changes: 177 additions & 40 deletions numpy/core/arrayprint.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,13 +29,14 @@ def product(x, y): return x*y
_line_width = 75
_nan_str = 'nan'
_inf_str = 'inf'
_formatter = None # formatting function for array elements

if sys.version_info[0] >= 3:
from functools import reduce

def set_printoptions(precision=None, threshold=None, edgeitems=None,
linewidth=None, suppress=None,
nanstr=None, infstr=None):
nanstr=None, infstr=None, formatter=None):
"""
Set printing options.

Expand All @@ -62,10 +63,38 @@ def set_printoptions(precision=None, threshold=None, edgeitems=None,
String representation of floating point not-a-number (default nan).
infstr : str, optional
String representation of floating point infinity (default inf).
formatter : dict of callables, optional
If not None, the keys should indicate the type(s) that the respective
formatting function applies to. Callables should return a string.
Types that are not specified (by their corresponding keys) are handled
by the default formatters. Individual types for which a formatter
can be set are::

- 'bool'
- 'int'
- 'timeint' : a `numpy.timeinteger`
- 'float'
- 'longfloat' : 128-bit floats
- 'complexfloat'
- 'longcomplexfloat' : composed of two 128-bit floats
- 'numpy_str' : types `numpy.string_` and `numpy.unicode_`
- 'str' : all other strings

Other keys that can be used to set a group of types at once are::

- 'all' : sets all types
- 'int_kind' : sets 'int' and 'timeint'
- 'float_kind' : sets 'float' and 'longfloat'
- 'complex_kind' : sets 'complexfloat' and 'longcomplexfloat'
- 'str_kind' : sets 'str' and 'numpystr'

See Also
--------
get_printoptions, set_string_function
get_printoptions, set_string_function, array2string

Notes
-----
`formatter` is always reset with a call to `set_printoptions`.

Examples
--------
Expand All @@ -91,15 +120,26 @@ def set_printoptions(precision=None, threshold=None, edgeitems=None,
>>> x**2 - (x + eps)**2
array([-0., -0., 0., 0.])

A custom formatter can be used to display array elements as desired:

>>> np.set_printoptions(formatter={'all':lambda x: 'int: '+str(-x)})
>>> x = np.arange(3)
>>> x
array([int: 0, int: -1, int: -2])
>>> np.set_printoptions() # formatter gets reset
>>> x
array([0, 1, 2])

To put back the default options, you can use:

>>> np.set_printoptions(edgeitems=3,infstr='Inf',
... linewidth=75, nanstr='NaN', precision=8,
... suppress=False, threshold=1000)
>>> np.set_printoptions(edgeitems=3,infstr='inf',
... linewidth=75, nanstr='nan', precision=8,
... suppress=False, threshold=1000, formatter=None)
"""

global _summaryThreshold, _summaryEdgeItems, _float_output_precision, \
_line_width, _float_output_suppress_small, _nan_str, _inf_str
_line_width, _float_output_suppress_small, _nan_str, _inf_str, \
_formatter
if linewidth is not None:
_line_width = linewidth
if threshold is not None:
Expand All @@ -114,6 +154,7 @@ def set_printoptions(precision=None, threshold=None, edgeitems=None,
_nan_str = nanstr
if infstr is not None:
_inf_str = infstr
_formatter = formatter

def get_printoptions():
"""
Expand All @@ -131,6 +172,7 @@ def get_printoptions():
- suppress : bool
- nanstr : str
- infstr : str
- formatter : dict of callables

For a full description of these options, see `set_printoptions`.

Expand All @@ -145,7 +187,8 @@ def get_printoptions():
linewidth=_line_width,
suppress=_float_output_suppress_small,
nanstr=_nan_str,
infstr=_inf_str)
infstr=_inf_str,
formatter=_formatter)
return d

def _leading_trailing(a):
Expand Down Expand Up @@ -173,7 +216,7 @@ def _boolFormatter(x):


def _array2string(a, max_line_width, precision, suppress_small, separator=' ',
prefix=""):
prefix="", formatter=None):

if max_line_width is None:
max_line_width = _line_width
Expand All @@ -184,51 +227,86 @@ def _array2string(a, max_line_width, precision, suppress_small, separator=' ',
if suppress_small is None:
suppress_small = _float_output_suppress_small

if formatter is None:
formatter = _formatter

if a.size > _summaryThreshold:
summary_insert = "..., "
data = _leading_trailing(a)
else:
summary_insert = ""
data = ravel(a)

formatdict = {'bool' : _boolFormatter,
'int' : IntegerFormat(data),
'timeint' : str,
'float' : FloatFormat(data, precision, suppress_small),
'longfloat' : LongFloatFormat(precision),
'complexfloat' : ComplexFormat(data, precision,
suppress_small),
'longcomplexfloat' : LongComplexFormat(precision),
'numpystr' : repr,
'str' : str}
if formatter is not None:
fkeys = [k for k in formatter.keys() if formatter[k] is not None]
if 'all' in fkeys:
for key in formatdict.keys():
formatdict[key] = formatter['all']
if 'int_kind' in fkeys:
for key in ['int', 'timeint']:
formatdict[key] = formatter['int_kind']
if 'float_kind' in fkeys:
for key in ['float', 'longfloat']:
formatdict[key] = formatter['float_kind']
if 'complex_kind' in fkeys:
for key in ['complexfloat', 'longcomplexfloat']:
formatdict[key] = formatter['complex_kind']
if 'str_kind' in fkeys:
for key in ['numpystr', 'str']:
formatdict[key] = formatter['str_kind']
for key in formatdict.keys():
if key in fkeys:
formatdict[key] = formatter[key]

try:
format_function = a._format
msg = "The `_format` attribute is deprecated in Numpy 2.0 and " \
"will be removed in 2.1. Use the `formatter` kw instead."
import warnings
warnings.warn(msg, DeprecationWarning)
except AttributeError:
# find the right formatting function for the array
dtypeobj = a.dtype.type
if issubclass(dtypeobj, _nt.bool_):
# make sure True and False line up.
format_function = _boolFormatter
format_function = formatdict['bool']
elif issubclass(dtypeobj, _nt.integer):
if issubclass(dtypeobj, _nt.timeinteger):
format_function = str
format_function = formatdict['timeint']
else:
max_str_len = max(len(str(maximum.reduce(data))),
len(str(minimum.reduce(data))))
format = '%' + str(max_str_len) + 'd'
format_function = lambda x: _formatInteger(x, format)
format_function = formatdict['int']
elif issubclass(dtypeobj, _nt.floating):
if issubclass(dtypeobj, _nt.longfloat):
format_function = LongFloatFormat(precision)
format_function = formatdict['longfloat']
else:
format_function = FloatFormat(data, precision, suppress_small)
format_function = formatdict['float']
elif issubclass(dtypeobj, _nt.complexfloating):
if issubclass(dtypeobj, _nt.clongfloat):
format_function = LongComplexFormat(precision)
format_function = formatdict['longcomplexfloat']
else:
format_function = ComplexFormat(data, precision, suppress_small)
elif issubclass(dtypeobj, _nt.unicode_) or \
issubclass(dtypeobj, _nt.string_):
format_function = repr
format_function = formatdict['complexfloat']
elif issubclass(dtypeobj, (_nt.unicode_, _nt.string_)):
format_function = formatdict['numpystr']
else:
format_function = str
format_function = formatdict['str']

next_line_prefix = " " # skip over "["
next_line_prefix += " "*len(prefix) # skip over array(
# skip over "["
next_line_prefix = " "
# skip over array(
next_line_prefix += " "*len(prefix)

lst = _formatArray(a, format_function, len(a.shape), max_line_width,
next_line_prefix, separator,
_summaryEdgeItems, summary_insert)[:-1]

return lst

def _convert_arrays(obj):
Expand All @@ -243,9 +321,9 @@ def _convert_arrays(obj):
return tuple(newtup)


def array2string(a, max_line_width = None, precision = None,
suppress_small = None, separator=' ', prefix="",
style=repr):
def array2string(a, max_line_width=None, precision=None,
suppress_small=None, separator=' ', prefix="",
style=repr, formatter=None):
"""
Return a string representation of an array.

Expand Down Expand Up @@ -273,16 +351,49 @@ def array2string(a, max_line_width = None, precision = None,
output correctly.
style : function, optional
A function that accepts an ndarray and returns a string. Used only
when the shape of `a` is equal to ().
when the shape of `a` is equal to ``()``, i.e. for 0-D arrays.
formatter : dict of callables, optional
If not None, the keys should indicate the type(s) that the respective
formatting function applies to. Callables should return a string.
Types that are not specified (by their corresponding keys) are handled
by the default formatters. Individual types for which a formatter
can be set are::

- 'bool'
- 'int'
- 'timeint' : a `numpy.timeinteger`
- 'float'
- 'longfloat' : 128-bit floats
- 'complexfloat'
- 'longcomplexfloat' : composed of two 128-bit floats
- 'numpy_str' : types `numpy.string_` and `numpy.unicode_`
- 'str' : all other strings

Other keys that can be used to set a group of types at once are::

- 'all' : sets all types
- 'int_kind' : sets 'int' and 'timeint'
- 'float_kind' : sets 'float' and 'longfloat'
- 'complex_kind' : sets 'complexfloat' and 'longcomplexfloat'
- 'str_kind' : sets 'str' and 'numpystr'

Returns
-------
array_str : str
String representation of the array.

Raises
------
TypeError : if a callable in `formatter` does not return a string.

See Also
--------
array_str, array_repr, set_printoptions
array_str, array_repr, set_printoptions, get_printoptions

Notes
-----
If a formatter is specified for a certain type, the `precision` keyword is
ignored for that type.

Examples
--------
Expand All @@ -291,12 +402,24 @@ def array2string(a, max_line_width = None, precision = None,
... suppress_small=True)
[ 0., 1., 2., 3.]

>>> x = np.arange(3.)
>>> np.array2string(x, formatter={'float_kind':lambda x: "%.2f" % x})
'[0.00 1.00 2.00]'

>>> x = np.arange(3)
>>> np.array2string(x, formatter={'int':lambda x: hex(x)})
'[0x0L 0x1L 0x2L]'

"""

if a.shape == ():
x = a.item()
try:
lst = a._format(x)
msg = "The `_format` attribute is deprecated in Numpy 2.0 and " \
"will be removed in 2.1. Use the `formatter` kw instead."
import warnings
warnings.warn(msg, DeprecationWarning)
except AttributeError:
if isinstance(x, tuple):
x = _convert_arrays(x)
Expand All @@ -306,7 +429,7 @@ def array2string(a, max_line_width = None, precision = None,
lst = "[]"
else:
lst = _array2string(a, max_line_width, precision, suppress_small,
separator, prefix)
separator, prefix, formatter=formatter)
return lst

def _extendLine(s, line, word, max_line_len, next_line_prefix):
Expand Down Expand Up @@ -392,7 +515,12 @@ def __init__(self, data, precision, suppress_small, sign=False):
self.exp_format = False
self.large_exponent = False
self.max_str_len = 0
self.fillFormat(data)
try:
self.fillFormat(data)
except (TypeError, NotImplementedError):
# if reduce(data) fails, this instance will not be called, just
# instantiated in formatdict.
pass

def fillFormat(self, data):
import numeric as _nc
Expand Down Expand Up @@ -490,11 +618,22 @@ def _digits(x, precision, format):

_MAXINT = sys.maxint
_MININT = -sys.maxint-1
def _formatInteger(x, format):
if _MININT < x < _MAXINT:
return format % x
else:
return "%s" % x
class IntegerFormat(object):
def __init__(self, data):
try:
max_str_len = max(len(str(maximum.reduce(data))),
len(str(minimum.reduce(data))))
self.format = '%' + str(max_str_len) + 'd'
except TypeError, NotImplementedError:
# if reduce(data) fails, this instance will not be called, just
# instantiated in formatdict.
pass

def __call__(self, x):
if _MININT < x < _MAXINT:
return self.format % x
else:
return "%s" % x

class LongFloatFormat(object):
# XXX Have to add something to determine the width to use a la FloatFormat
Expand Down Expand Up @@ -552,5 +691,3 @@ def __call__(self, x):
else:
i = i + 'j'
return r + i

## end
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