Python numpy.can_cast函数代码示例

def validate_datatype(validator, datatype, instance, schema):
    if isinstance(instance, list):
        array = inline_data_asarray(instance)
        in_datatype, _ = numpy_dtype_to_asdf_datatype(array.dtype)
    elif isinstance(instance, dict):
        if 'datatype' in instance:
            in_datatype = instance['datatype']
        elif 'data' in instance:
            array = inline_data_asarray(instance['data'])
            in_datatype, _ = numpy_dtype_to_asdf_datatype(array.dtype)
        else:
            raise ValidationError("Not an array")
    elif isinstance(instance, (np.ndarray, NDArrayType)):
        in_datatype, _ = numpy_dtype_to_asdf_datatype(instance.dtype)
    else:
        raise ValidationError("Not an array")

    if datatype == in_datatype:
        return

    if schema.get('exact_datatype', False):
        yield ValidationError(
            "Expected datatype '{0}', got '{1}'".format(
                datatype, in_datatype))

    np_datatype = asdf_datatype_to_numpy_dtype(datatype)
    np_in_datatype = asdf_datatype_to_numpy_dtype(in_datatype)

    if not np_datatype.fields:
        if np_in_datatype.fields:
            yield ValidationError(
                "Expected scalar datatype '{0}', got '{1}'".format(
                    datatype, in_datatype))

        if not np.can_cast(np_in_datatype, np_datatype, 'safe'):
            yield ValidationError(
                "Can not safely cast from '{0}' to '{1}' ".format(
                    in_datatype, datatype))

    else:
        if not np_in_datatype.fields:
            yield ValidationError(
                "Expected structured datatype '{0}', got '{1}'".format(
                    datatype, in_datatype))

        if len(np_in_datatype.fields) != len(np_datatype.fields):
            yield ValidationError(
                "Mismatch in number of columns: "
                "Expected {0}, got {1}".format(
                    len(datatype), len(in_datatype)))

        for i in range(len(np_datatype.fields)):
            in_type = np_in_datatype[i]
            out_type = np_datatype[i]
            if not np.can_cast(in_type, out_type, 'safe'):
                yield ValidationError(
                    "Can not safely cast to expected datatype: "
                    "Expected {0}, got {1}".format(
                        numpy_dtype_to_asdf_datatype(out_type)[0],
                        numpy_dtype_to_asdf_datatype(in_type)[0]))

    def sum(self, axis=None):
        """Sum the matrix over the given axis.  If the axis is None, sum
        over both rows and columns, returning a scalar.
        """
        # The spmatrix base class already does axis=0 and axis=1 efficiently
        # so we only do the case axis=None here
        if axis is None:
            return self.data.sum()
        elif (not hasattr(self, 'blocksize') and
              axis in self._swap(((1, -1), (0, 2)))[0]):
            # faster than multiplication for large minor axis in CSC/CSR
            # Mimic numpy's casting.
            if np.issubdtype(self.dtype, np.float_):
                res_dtype = np.float_
            elif (self.dtype.kind == 'u' and
                  np.can_cast(self.dtype, np.uint)):
                res_dtype = np.uint
            elif np.can_cast(self.dtype, np.int_):
                res_dtype = np.int_
            else:
                res_dtype = self.dtype
            ret = np.zeros(len(self.indptr) - 1, dtype=res_dtype)

            major_index, value = self._minor_reduce(np.add)
            ret[major_index] = value
            ret = np.asmatrix(ret)
            if axis % 2 == 1:
                ret = ret.T
            return ret
        else:
            return spmatrix.sum(self, axis)

def get_sum_dtype(dtype):
    """Mimic numpy's casting for np.sum"""
    if dtype.kind == 'u' and np.can_cast(dtype, np.uint):
        return np.uint
    if np.can_cast(dtype, np.int_):
        return np.int_
    return dtype

    def sum(self, axis=None):
        """Sum the matrix over the given axis.  If the axis is None, sum
        over both rows and columns, returning a scalar.
        """
        # We use multiplication by an array of ones to achieve this.
        # For some sparse matrix formats more efficient methods are
        # possible -- these should override this function.
        m, n = self.shape

        # Mimic numpy's casting.
        if np.issubdtype(self.dtype, np.float_):
            res_dtype = np.float_
        elif (self.dtype.kind == 'u' and
              np.can_cast(self.dtype, np.uint)):
            res_dtype = np.uint
        elif np.can_cast(self.dtype, np.int_):
            res_dtype = np.int_
        else:
            res_dtype = self.dtype

        if axis is None:
            # sum over rows and columns
            return (self * np.asmatrix(np.ones((n, 1), dtype=res_dtype))).sum()

        if axis < 0:
            axis += 2
        if axis == 0:
            # sum over columns
            return np.asmatrix(np.ones((1, m), dtype=res_dtype)) * self
        elif axis == 1:
            # sum over rows
            return self * np.asmatrix(np.ones((n, 1), dtype=res_dtype))
        else:
            raise ValueError("axis out of bounds")

def transform_scalars(dataset, constant=0):
    """Add a constant to the data set"""

    from tomviz import utils
    import numpy as np

    scalars = utils.get_scalars(dataset)
    if scalars is None:
        raise RuntimeError("No scalars found!")

    # Try to be a little smart so that we don't always just produce a
    # double-precision output
    newMin = np.min(scalars) + constant
    newMax = np.max(scalars) + constant
    if (constant).is_integer() and newMin.is_integer() and newMax.is_integer():
        # Let ints be ints!
        constant = int(constant)
        newMin = int(newMin)
        newMax = int(newMax)
    for dtype in [np.uint8, np.int8, np.uint16, np.int16, np.uint32, np.int32,
                  np.uint64, np.int64, np.float32, np.float64]:
        if np.can_cast(newMin, dtype) and np.can_cast(newMax, dtype):
            constant = np.array([constant], dtype=dtype)
            break

    # numpy should cast to an appropriate output type to avoid overflow
    result = scalars + constant

    utils.set_scalars(dataset, result)

 def test_can_cast_record(self):
     import numpy as np
     rec1 = np.dtype([('x', int), ('y', float)])
     rec2 = np.dtype([('x', float), ('y', float)])
     rec3 = np.dtype([('y', np.float64), ('x', float)])
     assert not np.can_cast(rec1, rec2, 'equiv')
     assert np.can_cast(rec2, rec3, 'equiv')
     assert np.can_cast(rec1, rec2)

    def resolve(self, identifier, additional_namespace=None, strip_units=False):
        '''
        The additional_namespace (e.g. the local/global namespace) will only
        be used if the namespace does not contain any user-defined namespace.
        '''        
        # We save tuples of (namespace description, referred object) to
        # give meaningful warnings in case of duplicate definitions
        matches = []
        
        if self.is_explicit or additional_namespace is None: 
            namespaces = self.namespaces
        else:            
            namespaces = OrderedDict(self.namespaces)
            # Add the additional namespace in the end
            description, namespace = additional_namespace
            namespaces[description] = namespace
        
        for description, namespace in namespaces.iteritems():
            if identifier in namespace:
                matches.append((description, namespace[identifier]))            

        if len(matches) == 0:
            # No match at all
            raise KeyError(('The identifier "%s" could not be resolved.') % 
                           (identifier))
        elif len(matches) > 1:
            # Possibly, all matches refer to the same object
            first_obj = matches[0][1]
            if not all([(m[1] is first_obj) or _same_function(m[1], first_obj)
                        for m in matches]):
                _conflict_warning(('The name "%s" refers to different objects '
                                   'in different namespaces used for resolving. '
                                   'Will use the object from the %s namespace '
                                   'with the value %r') %
                                  (identifier, matches[0][0],
                                   first_obj), matches[1:])
                    
        # use the first match (according to resolution order)
        resolved = matches[0][1]

        # Remove units
        if strip_units and isinstance(resolved, Quantity):
            if resolved.ndim == 0:
                resolved = float(resolved)
            else:
                resolved = np.asarray(resolved)

        # Use standard Python types if possible
        if not isinstance(resolved, np.ndarray) and hasattr(resolved, 'dtype'):
            numpy_type = resolved.dtype
            if np.can_cast(numpy_type, np.int_):
                resolved = int(resolved)
            elif np.can_cast(numpy_type, np.float_):
                resolved = float(resolved)
            elif np.can_cast(numpy_type, np.complex_):
                resolved = complex(resolved)

        return resolved

    def __new__(cls, value, unit=None, dtype=None, copy=True, order=None,
                subok=False, ndmin=0):

        if unit is not None:
            # convert unit first, to avoid multiple string->unit conversions
            unit = Unit(unit)

        # optimize speed for Quantity with no dtype given, copy=False
        if isinstance(value, Quantity):
            if unit is not None and unit is not value.unit:
                value = value.to(unit)
                # the above already makes a copy (with float dtype)
                copy = False

            if not subok and type(value) is not cls:
                value = value.view(cls)

            if dtype is None:
                if not copy:
                    return value

                if not np.can_cast(np.float32, value.dtype):
                    dtype = np.float

            return np.array(value, dtype=dtype, copy=copy, order=order,
                            subok=True, ndmin=ndmin)

        # Maybe list/tuple of Quantity? short-circuit array for speed
        if(not isinstance(value, np.ndarray) and isiterable(value) and
           all(isinstance(v, Quantity) for v in value)):
            if unit is None:
                unit = value[0].unit
            value = [q.to(unit).value for q in value]
            copy = False  # copy already made

        else:
            if unit is None:
                unit = dimensionless_unscaled

        value = np.array(value, dtype=dtype, copy=copy, order=order,
                         subok=False, ndmin=ndmin)

        # check that array contains numbers or long int objects
        if (value.dtype.kind in 'OSU' and
            not (value.dtype.kind == 'O' and
                 isinstance(value.item(() if value.ndim == 0 else 0),
                            numbers.Number))):
            raise TypeError("The value must be a valid Python or "
                            "Numpy numeric type.")

        # by default, cast any integer, boolean, etc., to float
        if dtype is None and not np.can_cast(np.float32, value.dtype):
            value = value.astype(np.float)

        value = value.view(cls)
        value._unit = unit

        return value

 def can_cast1(args, ty_ins):
     for i in six.moves.range(nin):
         if args[i].const is None:
             if not numpy.can_cast(args[i].ty, ty_ins[i]):
                 return False
         else:
             if not numpy.can_cast(args[i].const, ty_ins[i]):
                 return False
     return True

def gentle_asarray(a, dtype):
    """
    Performs an asarray that doesn't cause a copy if the byteorder is
    different.  It also ignores column name differences -- the
    resulting array will have the column names from the given dtype.
    """
    out_dtype = np.dtype(dtype)
    if isinstance(a, np.ndarray):
        in_dtype = a.dtype
        # Non-table array
        if in_dtype.fields is None and out_dtype.fields is None:
            if np.can_cast(in_dtype, out_dtype, 'equiv'):
                return a
            else:
                return np.asanyarray(a, dtype=out_dtype)
        elif in_dtype.fields is not None and out_dtype.fields is not None:
            if in_dtype == out_dtype:
                return a
            in_names = {n.lower() for n in in_dtype.names}
            out_names = {n.lower() for n in out_dtype.names}
            if in_names == out_names:
                # Change the dtype name to match the fits record names
                # as the mismatch causes case insensitive access to fail
                out_dtype.names = in_dtype.names
            else:
                raise ValueError(
                    "Column names don't match schema. "
                    "Schema has {0}. Data has {1}".format(
                        str(out_names.difference(in_names)),
                        str(in_names.difference(out_names))))

            new_dtype = []
            for i in range(len(out_dtype.fields)):
                in_type = in_dtype[i]
                out_type = out_dtype[i]
                if in_type.subdtype is None:
                    type_str = in_type.str
                else:
                    type_str = in_type.subdtype[0].str
                if np.can_cast(in_type, out_type, 'equiv'):
                    new_dtype.append(
                        (out_dtype.names[i],
                         type_str,
                         in_type.shape))
                else:
                    return np.asanyarray(a, dtype=out_dtype)
            return a.view(dtype=np.dtype(new_dtype))
        else:
            return np.asanyarray(a, dtype=out_dtype)
    else:
        try:
            a = np.asarray(a, dtype=out_dtype)
        except Exception:
            raise ValueError("Can't convert {0!s} to ndarray".format(type(a)))
        return a

 def analyze(aDataObject, bDataObject,
             epsilonValue=0.0, epsilonPercent=None):
     """
     analyze the differences between the two data sets
     updates the two data objects with additional masks
     and returns data object containing diff data and masks
     """
     shape = aDataObject.data.shape
     assert(bDataObject.data.shape == shape)
     assert(np.can_cast(aDataObject.data.dtype, bDataObject.data.dtype) or
            np.can_cast(bDataObject.data.dtype, aDataObject.data.dtype))
     
     # do some basic analysis on the individual data sets
     aDataObject.self_analysis()
     bDataObject.self_analysis()
     
     # where is the shared valid data?
     valid_in_both  = aDataObject.masks.valid_mask  & bDataObject.masks.valid_mask
     ignore_in_both = aDataObject.masks.ignore_mask | bDataObject.masks.ignore_mask
     
     # get our shared data type and fill value
     sharedType, fill_data_value = DiffInfoObject._get_shared_type_and_fill_value(aDataObject.data,
                                                                                  bDataObject.data,
                                                                                  aDataObject.select_fill_value(),
                                                                                  bDataObject.select_fill_value())
     
     # we can't continue if we don't have a fill value
     assert(fill_data_value is not None)
     
     # construct our diff'ed data set
     raw_diff = np.zeros(shape, dtype=sharedType)
     raw_diff[~valid_in_both] = fill_data_value # throw away invalid data
     # compute difference, using shared type in computation
     raw_diff[valid_in_both] = bDataObject.data[valid_in_both].astype(sharedType) -  \
                               aDataObject.data[valid_in_both].astype(sharedType)
     
     # the valid data which is too different between the two sets according to the given epsilon
     outside_epsilon_mask = np.zeros(shape, dtype=np.bool)
     if (epsilonValue   is not None) :
         outside_epsilon_mask |= (abs(raw_diff) > epsilonValue) & valid_in_both
     if (epsilonPercent is not None) :
         outside_epsilon_mask |= (abs(raw_diff) > abs(aDataObject.data * (float(epsilonPercent) / 100.0))) & valid_in_both
     
     # mismatch points = mismatched nans, mismatched missing-values, differences that are too large 
     mismatch_pt_mask = ( (aDataObject.masks.non_finite_mask ^ bDataObject.masks.non_finite_mask) |
                          (aDataObject.masks.missing_mask    ^ bDataObject.masks.missing_mask)    |
                          outside_epsilon_mask )
     
     # make our diff data object
     diff_data_object = DataObject(raw_diff, fillValue=fill_data_value)
     diff_data_object.masks = DiffMaskSetObject(ignore_in_both, valid_in_both,
                                                mismatch_pt_mask, outside_epsilon_mask)
     
     return diff_data_object

def gentle_asarray(a, dtype):
    """
    Performs an asarray that doesn't cause a copy if the byteorder is
    different.  It also ignores column name differences -- the
    resulting array will have the column names from the given dtype.
    """
    out_dtype = np.dtype(dtype)
    if isinstance(a, np.ndarray):
        in_dtype = a.dtype
        # Non-table array
        if in_dtype.fields is None and out_dtype.fields is None:
            if np.can_cast(in_dtype, out_dtype, 'equiv'):
                return a
            else:
                return np.asanyarray(a, dtype=out_dtype)
        elif in_dtype.fields is not None and out_dtype.fields is not None:
            if in_dtype == out_dtype:
                return a
            if len(in_dtype) != len(out_dtype):
                raise ValueError(
                    "Wrong number of columns.  Expected {0}, got {1}".format(
                        len(out_dtype), len(in_dtype)))
            new_dtype = []
            # Change the dtype name to match the fits record names
            # as the mismatch causes case insensitive access to fail
            if hasattr(in_dtype, 'names') and hasattr(out_dtype, 'names'):
                out_dtype.names = in_dtype.names
            for i in range(len(out_dtype.fields)):
                in_type = in_dtype[i]
                out_type = out_dtype[i]
                if in_type.subdtype is None:
                    type_str = in_type.str
                else:
                    type_str = in_type.subdtype[0].str
                if np.can_cast(in_type, out_type, 'equiv'):
                    new_dtype.append(
                        (out_dtype.names[i],
                         type_str,
                         in_type.shape))
                else:
                    return np.asanyarray(a, dtype=out_dtype)
            return a.view(dtype=np.dtype(new_dtype))
        else:
            return np.asanyarray(a, dtype=out_dtype)
    else:
        try:
            a = np.asarray(a, dtype=out_dtype)
        except:
            raise ValueError("Can't convert {0!s} to ndarray".format(type(a)))
        return a

def upcast(*args):
    """Returns the nearest supported sparse dtype for the
    combination of one or more types.

    upcast(t0, t1, ..., tn) -> T  where T is a supported dtype

    Examples
    --------

    >>> upcast('int32')
    <type 'numpy.int32'>
    >>> upcast('bool')
    <type 'numpy.int8'>
    >>> upcast('int32','float32')
    <type 'numpy.float64'>
    >>> upcast('bool',complex,float)
    <type 'numpy.complex128'>

    """

    t = _upcast_memo.get(hash(args))
    if t is not None:
        return t

    upcast = np.find_common_type(args, [])

    for t in supported_dtypes:
        if np.can_cast(upcast, t):
            _upcast_memo[hash(args)] = t
            return t

    raise TypeError('no supported conversion for types: %s' % args)

    def __init__(self, element_strategy, shape, dtype, fill, unique):
        self.shape = tuple(shape)
        self.fill = fill
        check_argument(shape,
                       u'Array shape must have at least one dimension, '
                       u'provided shape was {}', shape)
        check_argument(all(isinstance(s, int) for s in shape),
                       u'Array shape must be integer in each dimension, '
                       u'provided shape was {}', shape)
        self.array_size = int(np.prod(shape))
        self.dtype = dtype
        self.element_strategy = element_strategy
        self.unique = unique

        # Used by self.insert_element to check that the value can be stored
        # in the array without e.g. overflowing.  See issue #1385.
        if dtype.kind in (u'i', u'u'):
            self.check_cast = lambda x: np.can_cast(x, self.dtype, 'safe')
        elif dtype.kind == u'f' and dtype.itemsize == 2:
            max_f2 = (2. - 2 ** -10) * 2 ** 15
            self.check_cast = lambda x: \
                (not np.isfinite(x)) or (-max_f2 <= x <= max_f2)
        elif dtype.kind == u'f' and dtype.itemsize == 4:
            max_f4 = (2. - 2 ** -23) * 2 ** 127
            self.check_cast = lambda x: \
                (not np.isfinite(x)) or (-max_f4 <= x <= max_f4)
        else:
            self.check_cast = lambda x: True

    def set_data(self, A):
        """
        Set the image array

        ACCEPTS: numpy/PIL Image A
        """
        # check if data is PIL Image without importing Image
        if hasattr(A, 'getpixel'):
            self._A = pil_to_array(A)
        else:
            self._A = cbook.safe_masked_invalid(A)

        if (self._A.dtype != np.uint8 and
                not np.can_cast(self._A.dtype, np.float)):
            raise TypeError("Image data can not convert to float")

        if (self._A.ndim not in (2, 3) or
                (self._A.ndim == 3 and self._A.shape[-1] not in (3, 4))):
            raise TypeError("Invalid dimensions for image data")

        self._imcache = None
        self._rgbacache = None
        self._oldxslice = None
        self._oldyslice = None
        self.stale = True