python numpy savetxt
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python numpy savetxt
提问by astrofrog
Can someone indicate what I am doing wrong here?
有人可以指出我在这里做错了什么吗？
import numpy as np
a = np.array([1,2,3,4,5],dtype=int)
b = np.array(['a','b','c','d','e'],dtype='|S1')
np.savetxt('test.txt',zip(a,b),fmt="%i %s")
The output is:
输出是：
Traceback (most recent call last):
File "loadtxt.py", line 6, in <module>
np.savetxt('test.txt',zip(a,b),fmt="%i %s")
File "/Users/tom/Library/Python/2.6/site-packages/numpy/lib/io.py", line 785, in savetxt
fh.write(format % tuple(row) + '\n')
TypeError: %d format: a number is required, not numpy.string_
回答by SilentGhost
You need to construct you array differently:
您需要以不同的方式构造数组：
z = np.array(zip([1,2,3,4,5], ['a','b','c','d','e']), dtype=[('int', int), ('str', '|S1')])
np.savetxt('test.txt', z, fmt='%i %s')
when you're passing a sequence, savetextperforms asarray(sequence)calland resulting array is of type |S4, that is all elements are strings! that's why you see this error.
当您传递一个序列时，savetext执行asarray(sequence)调用并且结果数组的类型为|S4，即所有元素都是字符串！这就是您看到此错误的原因。
回答by dalloliogm
If you want to save a CSV file you can also use the function rec2csv (included in matplotlib.mlab)
如果你想保存一个 CSV 文件，你也可以使用函数 rec2csv（包含在 matplotlib.mlab 中）
>>> from matplotlib.mlab import rec2csv
>>> rec = array([(1.0, 2), (3.0, 4)], dtype=[('x', float), ('y', int)])
>>> rec = array(zip([1,2,3,4,5], ['a','b','c','d','e']), dtype=[('x', int), ('y', str)])
>>> rec2csv(rec, 'recordfile.txt', delimiter=' ')
hopefully, one day pylab's developers will implement a decent support to writing csv files.
希望有朝一日 pylab 的开发人员能够实现对编写 csv 文件的体面支持。
回答by dwelch
I think the problem you are having is that you are passing tuples through the formating string and it can't interpret the tuple with %i. Try using fmt="%s", assuming this is what you are looking for as the output:
我认为您遇到的问题是您通过格式化字符串传递元组，并且它无法用 %i 解释元组。尝试使用 fmt="%s"，假设这是您要查找的输出：
1 a
2 b
3 c
4 d
5 e
