Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
314 views
in Technique[技术] by (71.8m points)

python - Numpy: Joining structured arrays?

Input

I have many numpy structured arrays in a list like this example:

import numpy

a1 = numpy.array([(1, 2), (3, 4), (5, 6)], dtype=[('x', int), ('y', int)])

a2 = numpy.array([(7,10), (8,11), (9,12)], dtype=[('z', int), ('w', float)])

arrays = [a1, a2]

Desired Output

What is the correct way to join them all together to create a unified structured array like the following?

desired_result = numpy.array([(1, 2, 7, 10), (3, 4, 8, 11), (5, 6, 9, 12)],
                             dtype=[('x', int), ('y', int), ('z', int), ('w', float)])

Current Approach

This is what I'm currently using, but it is very slow, so I suspect there must be a more efficent way.

from numpy.lib.recfunctions import append_fields

def join_struct_arrays(arrays):
    for array in arrays:
        try:
            result = append_fields(result, array.dtype.names, [array[name] for name in array.dtype.names], usemask=False)
        except NameError:
            result = array

    return result
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

You can also use the function merge_arrays of numpy.lib.recfunctions:

import numpy.lib.recfunctions as rfn
rfn.merge_arrays(arrays, flatten = True, usemask = False)

Out[52]: 
array([(1, 2, 7, 10.0), (3, 4, 8, 11.0), (5, 6, 9, 12.0)], 
     dtype=[('x', '<i4'), ('y', '<i4'), ('z', '<i4'), ('w', '<f8')])

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...