python - 从指定位置读取数据

Question

import CSV

#Get high temperatures from file.
filename = 'sitka_weather_07-2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)

    highs = []
    for row in reader:
        highs.append(row[1])

    print(highs)

我在学习提取和读取数据时遇到了上面的代码。

我不太明白 next() 的用法:

header_row = next(reader)

书上解释说，因为我们已经读取了标题行，所以循环将从实际数据开始的第二行开始

如果我们需要从第三行开始读怎么办？以下是正确的吗？

with open(filename) as f:
        reader = csv.reader(f)
        header_row = next(reader)
        row_1 = next(reader)

        highs = []
        for row in reader:
            highs.append(row[2])

        Print(highs)

这个问题可能很无聊，但我很困惑

Answer 1

下一个函数将光标向前移动一行，所以在代码段中是

header_row = next(reader)
row_1 = next(reader)
highs = []
for row in reader:
    highs.append(row[2])
Print(highs)

虽然这不是最好的方式，但该行确实从第三行开始。

如果你想直接访问行，试试这个

with open(filename) as f:
    reader = csv.reader(f)
    rows = list(reader)
    print rows[2]  # this will get you the third row