NumPy: Data type

Last update on August 19 2022 21:51:09 (UTC/GMT +8 hours)

Data type

A data type object describes how the bytes in the fixed-size block of memory corresponding to an array item should be interpreted. It describes the following aspects of the data:

Type of the data (integer, float, Python object, etc.)
Size of the data (number of bytes is in e.g. the integer)
Byte order of the data (little-endian or big-endian)
If the data type is structured, an aggregate of other data types,
- Type of the data (integer, float, Python object, etc.)
- Size of the data (how many bytes is in e.g. the integer)
- Byte order of the data (little-endian or big-endian)
- If the data type is structured, an aggregate of other data types, (e.g., describing an array item consisting of an integer and a float),
If the data type is a sub-array, what is its shape and data type.

Data type routines
Name	Description	Syntax
can_cast()	Returns True if cast between data types can occur according to the casting rule	numpy.can_cast(from_, to, casting='safe')
promote_types()	Returns the data type with the smallest size and smallest scalar kind to which both type1 and type2 may be safely cast.	numpy.promote_types(type1, type2)
min_scalar_type()	Returns the data type with the smallest size and smallest scalar kind which can hold its value.	numpy.min_scalar_type(a)
result_type()	Returns the type that results from applying the NumPy type promotion rules to the arguments.	numpy.result_type(*arrays_and_dtypes)
common_type()	Return a scalar type which is common to the input arrays.	numpy.common_type(*arrays)
obj2sctype()	Return the scalar dtype or NumPy equivalent of Python type of an object.	numpy.obj2sctype(rep, default=None)

Creating data types
Name	Description	Syntax
dtype	Create a data type object.	class numpy.dtype(obj, align=False, copy=False)
format_parser	Class to convert formats, names, titles description to a dtype.	class numpy.format_parser(formats, names, titles, aligned=False, byteorder=None)

Data type information
Name	Description	Syntax
finfo()	Machine limits for integer types.	class numpy.finfo(dtype)
iinfo()	Machine limits for integer types.	class numpy.iinfo(type)
MachAr()	Diagnosing machine parameters.	class numpy.MachAr(float_conv=<class 'float'>, int_conv=<class 'int'>, float_to_float=<class 'float'>, float_to_str=<function MachAr.<lambda>>, title='Python floating point number')

Data type testing
Name	Description	Syntax
issctype()	Determines whether the given object represents a scalar data-type.	numpy.iinfo(type)
issubdtype()	Returns True if first argument is a typecode lower/equal in type hierarchy.	numpy.issubdtype(arg1, arg2)
issubsctype()	Determine if the first argument is a subclass of the second argument.	numpy.issubsctype(arg1, arg2)
issubclass_()	Determine if a class is a subclass of a second class.	numpy.issubclass_(arg1, arg2)
find_common_type()	Determine common type following standard coercion rules.	numpy.find_common_type(array_types, scalar_types)

Miscellaneous
Name	Description	Syntax
typename()	Return a description for the given data type code.	numpy.typename(char)
sctype2char()	Return the string representation of a scalar dtype.	numpy.sctype2char(sctype)
mintypecode()	Return the character for the minimum-size type to which given types can be safely cast.	numpy.mintypecode(typechars, typeset='GDFgdf', default='d')

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