如何将 for 循环中的结果写入多个 CSV 文件

Question

我有

with open ('~/abc.csv', 'w') as f:
    write1 = csv.write(f)
    write1.writerow(['header1', 'header2', 'header3', 'header4'])

with open ('~/def.csv', 'w') as g:
    write2 = csv.write(g)
    write2.writerow(['header1', 'header2', 'header3', 'header4', 'header5', 'header6'])

for iteration in a_list:
    perform calculations
    result1 = ([h1, h2, h3, h4],[l1, l2, l3, l4],[m1, m2, m3, m4], ...,[])
    for pa in result1:
        write1.writerow(pa)

    def fun(result1):
        result2 = ([n1, n2, n3, n4, n5, n6],[p1, p2, p3, p4, p5, p6], [], ...[])
        for pb in result2:
             write2.writerow(pb)

期望两个 csv 文件为

'header1', 'header2', 'header3', 'header4'
h1, h2, h3, h4
l1, l2, l3, l4
m1, m2, m3, m4
      :

和

'header1', 'header2', 'header3', 'header4', 'header5', 'header6'
n1, n2, n3, n4, n5, n6
p1, p2, p3, p4, p5, p6

当所有迭代都完成时，这可以很容易地完成，并且可以使用 writer.writerows(pa) 轻松地将单独的 append(list) result1 和 result2 写入单独的文件。但是，我想在每次迭代中写入 csv 文件，这样如果由于某种原因不得不中断循环，我就不会错过。

谢谢！

Answer 1

您可以在上下文管理器中放置两个文件并拥有两个csv.writer对象（自 Python 2.7 起）：

with open ('~/abc.csv', 'w') as f, open ('~/def.csv', 'w') as g:
    writer1 = csv.writer(f)
    writer2 = csv.writer(g)

    writer1.writerow(['header1', 'header2', 'header3', 'header4'])    
    writer2.writerow(['header1', 'header2', 'header3', 'header4', 'header5', 'header6'])

    for iteration in a_list:
        # perform calculations
        for pa in result1:
            writer1.writerow(pa)
        for pb in result2:
            writer2.writerow(pb)

来自文档（对于 Python 2.7到3.5是相同的）。

对于不止一项，上下文管理器的处理就像嵌套了多个 with 语句一样：

with A() as a, B() as b:
    suite

相当于

with A() as a:
    with B() as b:
        suite

这表明另一种方法是让嵌套更深一层。

with open ('~/abc.csv', 'w') as f:
    with open ('~/def.csv', 'w') as g:
        writer1 = csv.writer(f)
        writer2 = csv.writer(g)
        ...