papyri
{ } Raw JSON

bundles / numpy 2.4.4 / numpy / rec / fromstring

function

numpy.rec:fromstring

source: /numpy/_core/records.py:752

Signature

def fromstring(datastring, dtype = None, shape = None, offset = 0, formats = None, names = None, titles = None, aligned = False, byteorder = None)

Summary

Create a record array from binary data

Extended Summary

Note that despite the name of this function it does not accept str instances.

Parameters

datastring : bytes-like

Buffer of binary data

dtype : data-type, optional

Valid dtype for all arrays

shape : int or tuple of ints, optional

Shape of each array.

offset : int, optional

Position in the buffer to start reading from.

formats, names, titles, aligned, byteorder

If dtype is None, these arguments are passed to numpy.format_parser to construct a dtype. See that function for detailed documentation.

Returns

: np.recarray

Record array view into the data in datastring. This will be readonly if datastring is readonly.

Examples

a = b'\x01\x02\x03abc'
✓
np.rec.fromstring(a, dtype='u1,u1,u1,S3')
✗
rec.array([(1, 2, 3, b'abc')],
          dtype=[('f0', 'u1'), ('f1', 'u1'), ('f2', 'u1'), ('f3', 'S3')])

grades_dtype = [('Name', (np.str_, 10)), ('Marks', np.float64),
                ('GradeLevel', np.int32)]
grades_array = np.array([('Sam', 33.3, 3), ('Mike', 44.4, 5),
                        ('Aadi', 66.6, 6)], dtype=grades_dtype)
✓
np.rec.fromstring(grades_array.tobytes(), dtype=grades_dtype)
✗
rec.array([('Sam', 33.3, 3), ('Mike', 44.4, 5), ('Aadi', 66.6, 6)],
          dtype=[('Name', '<U10'), ('Marks', '<f8'), ('GradeLevel', '<i4')])

s = '\x01\x02\x03abc'
np.rec.fromstring(s, dtype='u1,u1,u1,S3')
✓
Traceback (most recent call last):
  File "<doctest numpy.rec:fromstring[0]>", line 1, in <module>
    np.rec.fromstring(s, dtype='u1,u1,u1,S3')
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/records.py", line 824, in fromstring
    _array = recarray(shape, descr, buf=datastring, offset=offset)
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/records.py", line 402, in __new__
    self = ndarray.__new__(
        subtype, shape, (record, descr), buffer=buf,
        offset=offset, strides=strides, order=order
    )
TypeError: a bytes-like object is required, not 'str'

See also

numpy.frombuffer

Aliases

  • numpy.rec.fromstring