Python convert Python string to Numpy unicode string

Question

I cannot work out how to convert a Python string to a numpy unicode string

import numpy as np

py_str = "hello world"
#numpy_str = ?

What is a numpy unicode string? Are you using Python 2 or 3? — John Zwinck
– John Zwinck, Commented Mar 6, 2018 at 9:57
Why not np.array(py_str)? In Py3 that will be uncode. Or np.unicode_(py_str). Generally a single element array is more useful, though they share many of the same attributes and methods. — hpaulj
– hpaulj, Commented Mar 6, 2018 at 16:46

Cristian Ramon-Cortes · Accepted Answer · 2018-03-07 11:10:49Z

3

To convert a Python string to a numpy string you can simply use the numpy constructor.

>>> import numpy as np
>>> py_str = "hello world"
>>> numpy_str = np.string_(py_str)
>>> type(numpy_str)
<type 'numpy.string_'>

EDIT:

Following @hpaulj suggestion you may find that the dtype of numpy_str is string88 not unicode. Next, I add the code to convert it to unicode with the content, type, and dtype checks.

>>> numpy_str
'hello world'
>>> type(numpy_str)
<type 'numpy.string_'>
>>> numpy_str.dtype.name
'string88'

>>> numpy_unicode = numpy_str.astype(unicode)

>>> numpy_unicode
u'hello world'
>>> type(numpy_unicode)
<type 'numpy.unicode_'>
>>> numpy_unicode.dtype.name
'unicode352'

edited Mar 7, 2018 at 11:10

answered Mar 6, 2018 at 9:58

Cristian Ramon-Cortes

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1 Comment

Cristian Ramon-Cortes Over a year ago

@hpaulj Thanks. I updated the answer following your suggestion.

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