Python中返回None元素的巨大列表

Question

我有一个 CSV 文件，例如：

134;football
1457;soccer
12;volley
...

它正好有 4.992.909 行。代码是：

with open('/Users/someone/Desktop/python/sports.csv', 'r') as file1:        
    f = set(file1)

sports_label_list = [None] * 9985818

i = 0

for line in f:
    sports = line.split(';')[0]
    sports_label_list[i] = sports
    i = i + 1
    if 'football' in line:
        sports_label_list[i] = 'football'
    if 'volley' in line:
        sports_label_list[i] = 'volley'
    if 'basketball' in line:
        sports_label_list[i] = 'basketball'
    if 'soccer' in line:
        sports_label_list[i] = 'soccer'
    i = i + 1

当我打印以检查 sports_label_list 时，它运行正常（在偶数处显示数值，在奇数处显示运动名称）直到列表的 30000 元素附近。之后，它开始打印“无”。 CSV 文件没问题。有什么建议？谢谢！

Answer 1

文件可能有重复的行，设置消除。你为什么要把它放在一个集合中？不必要的内存使用。一个更好、更快的选择是逐步建立列表：

sports_label_list = []

with open('/Users/someone/Desktop/python/sports.csv', 'r') as file1:   
    for line in file1:
        number, sport = line.strip().split(";")
        sport_label_list.append(number)
        if sport in ("football", "soccer", "baseball", "basketball"):
            sport_label_list.append(sport)
        else:
            sport_label_list.append(None)