class numpy.dtype(obj, align=False, copy=False)
[source]
Create a data type object.
A numpy array is homogeneous, and contains elements described by a dtype object. A dtype object can be constructed from different combinations of fundamental numeric types.
Parameters: |
obj Object to be converted to a data type object. align : bool, optional Add padding to the fields to match what a C compiler would output for a similar C-struct. Can be copy : bool, optional Make a new copy of the data-type object. If |
---|
See also
Using array-scalar type:
>>> np.dtype(np.int16) dtype('int16')
Structured type, one field name ‘f1’, containing int16:
>>> np.dtype([('f1', np.int16)]) dtype([('f1', '<i2')])
Structured type, one field named ‘f1’, in itself containing a structured type with one field:
>>> np.dtype([('f1', [('f1', np.int16)])]) dtype([('f1', [('f1', '<i2')])])
Structured type, two fields: the first field contains an unsigned int, the second an int32:
>>> np.dtype([('f1', np.uint), ('f2', np.int32)]) dtype([('f1', '<u4'), ('f2', '<i4')])
Using array-protocol type strings:
>>> np.dtype([('a','f8'),('b','S10')]) dtype([('a', '<f8'), ('b', '|S10')])
Using comma-separated field formats. The shape is (2,3):
>>> np.dtype("i4, (2,3)f8") dtype([('f0', '<i4'), ('f1', '<f8', (2, 3))])
Using tuples. int
is a fixed type, 3 the field’s shape. void
is a flexible type, here of size 10:
>>> np.dtype([('hello',(int,3)),('world',np.void,10)]) dtype([('hello', '<i4', 3), ('world', '|V10')])
Subdivide int16
into 2 int8
’s, called x and y. 0 and 1 are the offsets in bytes:
>>> np.dtype((np.int16, {'x':(np.int8,0), 'y':(np.int8,1)})) dtype(('<i2', [('x', '|i1'), ('y', '|i1')]))
Using dictionaries. Two fields named ‘gender’ and ‘age’:
>>> np.dtype({'names':['gender','age'], 'formats':['S1',np.uint8]}) dtype([('gender', '|S1'), ('age', '|u1')])
Offsets in bytes, here 0 and 25:
>>> np.dtype({'surname':('S25',0),'age':(np.uint8,25)}) dtype([('surname', '|S25'), ('age', '|u1')])
base | |
descr | PEP3118 interface description of the data-type. |
fields | Dictionary of named fields defined for this data type, or None . |
hasobject | Boolean indicating whether this dtype contains any reference-counted objects in any fields or sub-dtypes. |
isalignedstruct | Boolean indicating whether the dtype is a struct which maintains field alignment. |
isbuiltin | Integer indicating how this dtype relates to the built-in dtypes. |
isnative | Boolean indicating whether the byte order of this dtype is native to the platform. |
metadata | |
name | A bit-width name for this data-type. |
names | Ordered list of field names, or None if there are no fields. |
ndim | Number of dimensions of the sub-array if this data type describes a sub-array, and 0 otherwise. |
shape | Shape tuple of the sub-array if this data type describes a sub-array, and () otherwise. |
str | The array-protocol typestring of this data-type object. |
subdtype | Tuple (item_dtype, shape) if this dtype describes a sub-array, and None otherwise. |
newbyteorder ([new_order]) | Return a new dtype with a different byte order. |
© 2008–2017 NumPy Developers
Licensed under the NumPy License.
https://docs.scipy.org/doc/numpy-1.14.2/reference/generated/numpy.dtype.html