如何將numpy列表輸出到cvs文件python 3.6中

Question

我有一個Python列表如下：

[(numpy.datetime64('2000-04-01'), 'pie'),
 (numpy.datetime64('2000-04-01'), 'apple'),
 (numpy.datetime64('2000-04-01'), 'orange'),
 (numpy.datetime64('2000-04-01'), 'mango'),
 (numpy.datetime64('2000-04-01'), 'pears')]

我希望它如下所示的csv文件輸出

|    date    |  item |
+------------+-------+
| 2000-04-01 | pie   |
| 2000-04-01 | apple |
|     ...    |  ...  |

Answer 1

我終於能夠輸出為csv文件。

import csv
with open('date_prop.csv','w',newline='') as out:
    csv_out=csv.writer(out)
    csv_out.writerow(['date','item'])
    for row in f2:
        csv_out.writerow(row)

Answer 2

簡單的Python文件編寫：

In [116]: with open('test','w') as f:
     ...:     print('   date   item', file=f)
     ...:     for t in alist:
     ...:         print('%s   %s'%t, file=f)
     ...:         
In [117]: cat test
   date   item
2000-04-01   pie
2000-04-01   apple
2000-04-01   orange
2000-04-01   mango
2000-04-01   pears

關鍵是str(np.datetime64('2000-04-01')的格式可以根據需要設置。

而且對象dtype數組可以使用帶有正確fmt savetxt編寫：

In [121]: arr = np.array(alist)
In [122]: arr
Out[122]: 
array([[numpy.datetime64('2000-04-01'), 'pie'],
       [numpy.datetime64('2000-04-01'), 'apple'],
       [numpy.datetime64('2000-04-01'), 'orange'],
       [numpy.datetime64('2000-04-01'), 'mango'],
       [numpy.datetime64('2000-04-01'), 'pears']], dtype=object)
In [123]: np.savetxt('test', arr, fmt='%s', delimiter=',', header='date item')
In [124]: cat test
# date item
2000-04-01,pie
2000-04-01,apple
2000-04-01,orange
2000-04-01,mango
2000-04-01,pears

我也可以創建一個結構化的數組並使用savetxt編寫它

In [125]: arr = np.array(alist, dtype='datetime64[D], U10')
In [126]: arr
Out[126]: 
array([('2000-04-01', 'pie'), ('2000-04-01', 'apple'),
       ('2000-04-01', 'orange'), ('2000-04-01', 'mango'),
       ('2000-04-01', 'pears')], dtype=[('f0', '<M8[D]'), ('f1', '<U10')])
In [127]: np.savetxt('test', arr, fmt='%s', delimiter=',  ', header='date   item
     ...: ')
In [128]: cat test
# date   item
2000-04-01,  pie
2000-04-01,  apple
2000-04-01,  orange
2000-04-01,  mango
2000-04-01,  pears