python csv閱讀器忽略空行

Question

我使用pythons csv閱讀器。 如何以忽略空行的方式使用以下代碼。

import csv
f1 = open ("ted.csv")
oldFile1 = csv.reader(f1, delimiter=',', quotechar='"')
oldList1 = list(oldFile1)
f2 = open ("ted2.csv")
newFile2 = csv.reader(f2, delimiter=',', quotechar='"')
newList2 = list(newFile2)

f1.close()
f2.close()

with open("ted.csv") as f1, open("ted2.csv") as f2, open('foo.csv', 'w') as out:
     r1, r2 = csv.reader(f1), csv.reader(f2)
     st = set((row[0], row[3]) for row in r1)
     wr = csv.writer(out)
     for row in (row for row in r2 if (row[0],row[3]) not in st):
           wr.writerow(row)

Answer 1

如果你的空白總是在第一行，那么馬呂斯的答案是最簡單的。 如果你有n空格開頭，或者你只是想跳過線的一些號碼，您可以使用itertools.islice()

先跳過N行

假設您要跳過前4行（空行或不空行）：

from itertools import islice
with open('csv2.csv', 'r') as f1, open('out.csv', 'w') as out:
    filt_f1 = islice(f1, 4, None)
    r1 = csv.reader(filt_f1)
    wr = csv.writer(out)
    for line in r1:
        ...

整個空行

如果您的文件中散布了空行，則可以使用itertools.filterfalse將其過濾掉。

import csv
from itertools import filterfalse
from itertools import chain

with open('csv1.csv', 'r') as f1, open('csv2.csv', 'r') as f2, open('out.csv', 'w') as out:
    # create an iterator without lines that start with '\n'
    filt_f1 = filterfalse(lambda line: line.startswith('\n'), f1)
    filt_f2 = filterfalse(lambda line: line.startswith('\n'), f2)

    # csv.reader consumes the filtered iterators
    r1, r2 = csv.reader(filt_f1), csv.reader(filt_f2)
    wr = csv.writer(out)

    # here insert your logic, I just write both to the same file
    for line in chain(r1, r2):
        wr.writerow(line)

其中csv1.csv是：

time,name,location
12345,Jean,Montreal

12346,Peter,Chicago

1234589,Doug,Boston

和csv2.csv（ 注意 ：此處未顯示，但csv2.csv在文件頂部有4個空行）：

123457,Scott,San Diego

123458,Jen,Miami

123459,Robert,Sacramento

輸出out.csv在整個過程中沒有空行：

time,name,location
12345,Jean,Montreal
12346,Peter,Chicago
1234589,Doug,Boston
123457,Scott,San Diego
123458,Jen,Miami
123459,Robert,Sacramento

Answer 2

如果您的csv文件以空行開頭，我認為您應該能夠在創建csv閱讀器之前使用readline()跳過該行：

with open("ted.csv") as f1, open("ted2.csv") as f2, open('foo.csv', 'w') as out:
    f1.readline()
    f2.readline()
    r1, r2 = csv.reader(f1), csv.reader(f2)