Issue in numpy data type?

Question

import numpy as np
c=np.dtype([('name','S20'), ('id','f4'), ('Marks','i1')])
d=np.array([('Ganesh',100.2,75) ], dtype = c)
print(d)

But the output I am getting is :

[(b'Ganesh', 100.2, 75)]

and the required output is :

[('Ganesh', 100.2, 75)]

If I am using multiple data in d then the output received is the desired one.

• juanpa.arrivillaga: b just means it's bytes type, which is the type you specified. The b is not actually in the string. Why does it matter? It's the correct way.

Answer 1

In [114]: c=np.dtype([('name','S20'), ('id','f4'), ('Marks','i1')]) 
In [115]: d=np.array([('Ganesh',100.2,75) ], dtype = c) 
In [116]: d 
Out[116]: 
array([(b'Ganesh', 100.2, 75)],
 dtype=[('name', 'S20'), ('id', '<f4'), ('Marks', 'i1')])

In PY3, the default string type is unicode. `b'foo' is bytestring. Use 'U' instead of 'S' if you want the default:

In [117]: c=np.dtype([('name','U20'), ('id','f4'), ('Marks','i1')]) 
In [118]: d=np.array([('Ganesh',100.2,75) ], dtype = c) 
In [119]: d 
Out[119]: 
array([('Ganesh', 100.2, 75)],
 dtype=[('name', '<U20'), ('id', '<f4'), ('Marks', 'i1')])