I have a set of lists that contain both strings and float numbers, such as:
import numpy as num
NAMES = num.array(['NAME_1', 'NAME_2', 'NAME_3'])
FLOATS = num.array([ 0.5 , 0.2 , 0.3 ])
DAT = num.column_stack((NAMES, FLOATS))
I want to stack these two lists together and write them to a text file in the form of columns; therefore, I want to use numpy.savetxt (if possible) to do this.
num.savetxt('test.txt', DAT, delimiter=" ")
When I do this, I get the following error:
>>> num.savetxt('test.txt', DAT, delimiter=" ")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Python/2.7/site-packages/numpy-1.8.0.dev_9597b1f_20120920-py2.7-macosx-10.8-x86_64.egg/numpy/lib/npyio.py", line 1047, in savetxt
fh.write(asbytes(format % tuple(row) + newline))
TypeError: float argument required, not numpy.string_
The ideal output file would look like:
NAME_1 0.5
NAME_2 0.2
NAME_3 0.3
How can I write both strings and float numbers to a text file, possibly avoiding using csv ( I want to make if readable for other people )? Is there another way of doing this instead of using numpy.savetxt?
The currently accepted answer does not actually address the question, which asks how to save lists that contain both strings and float numbers. For completeness I provide a fully working example, which is based, with some modifications, on the link given in @joris comment.
import numpy as np
names = np.array(['NAME_1', 'NAME_2', 'NAME_3'])
floats = np.array([ 0.1234 , 0.5678 , 0.9123 ])
ab = np.zeros(names.size, dtype=[('var1', 'U6'), ('var2', float)])
ab['var1'] = names
ab['var2'] = floats
np.savetxt('test.txt', ab, fmt="%10s %10.3f")
Update: This example also works properly in Python 3 by using the 'U6'
Unicode string dtype, when creating the ab
structured array, instead of the 'S6'
byte string. The latter dtype would work in Python 2.7, but would write strings like b'NAME_1'
in Python 3.
Source: Stackoverflow.com