python-格式化numpy数组并保存到* .txt

我想格式化一个numpy数组并将其保存在* .txt文件中

numpy数组如下所示：

a = [ 0.1   0.2   0.3   0.4   ... ] , [ 1.1   1.2   1.3   1.4   ... ] , ...

输出* .txt应该如下所示：

0   1:0.1   2:0.2   3:0.3   4:0.4   ...
0   1:1.1   2:1.2   3:1.3   1:1.4   ...
...

不知道该怎么做.

谢谢.

好吧,贾巴,谢谢.我把你的答案固定了一点

import numpy as np

a = np.array([[1,3,5,6], [4,2,4,6], [6,3,2,6]])

ret = ""

for i in range(a.shape[0]):
    ret += "0 "
    for j in range(a.shape[1]):
        ret += " %s:%s" % (j+1,float(a[i,j])) #have a space between the numbers for better reading and i think it should starts with 1 not with 0 ?!
ret +="\n"

fd = open("output.sparse", "w")
fd.write(ret)
fd.close()

您认为可以吗？

解决方法:

相当简单：

import numpy as np

a = np.array([[0.1, 0.2, 0.3, 0.4], [1.1, 1.2, 1.3, 1.4], [2.1, 2.2, 2.3, 2.4]])

with open("array.txt", 'w') as h:  
    for row in a:
        h.write("0")
        for n, col in enumerate(row):
            h.write("\t{0}:{1}".format(n+1, col))  # you can change the \t (tab) character to a number of spaces, if that's what you require
        h.write("\n")

并输出：

0       1:0.1   2:0.2   3:0.3   4:0.4
0       1:1.1   2:1.2   3:1.3   4:1.4
0       1:2.1   2:2.2   3:2.3   4:2.4

我最初的示例涉及大量磁盘写入.如果您的数组很大,那么效率可能会很低.但是,可以减少写入次数,例如：

with open("array.txt", 'w') as h:  
    for row in a:
        row_str = "0"
        for n, col in enumerate(row):
            row_str = "\t".join([row_str, "{0}:{1}".format(n+1, col)])
        h.write(''.join([row_str, '\n']))

您可以通过构造一个大字符串并将其写在末尾,将写入次数进一步减少到仅一次,但是在这种情况下真正有用的情况(例如,一个巨大的数组),则您会因构造一个大字符串而遇到内存问题巨大的弦.无论如何,取决于您.

标签：arrays,python,formatting,numpy
来源： https://codeday.me/bug/20191030/1969444.html