处理CSV数据时如何忽略第一行数据? [英] How to ignore the first line of data when processing CSV data?

问题描述

我要Python从一列CSV数据中打印最少的数字，但是最上面的一行是列号，我不希望Python考虑到最上面的一行.如何确保Python忽略第一行?

I am asking Python to print the minimum number from a column of CSV data, but the top row is the column number, and I don't want Python to take the top row into account. How can I make sure Python ignores the first line?

这是到目前为止的代码:

This is the code so far:

import csv

with open('all16.csv', 'rb') as inf:
    incsv = csv.reader(inf)
    column = 1                
    datatype = float          
    data = (datatype(column) for row in incsv)   
    least_value = min(data)

print least_value

您是否还可以解释自己在做什么，而不仅仅是给出代码?我对Python非常陌生，并希望确保我了解所有内容.

Could you also explain what you are doing, not just give the code? I am very very new to Python and would like to make sure I understand everything.

推荐答案

您可以使用csv模块的

You could use an instance of the csv module's Sniffer class to deduce the format of a CSV file and detect whether a header row is present along with the built-in next() function to skip over the first row only when necessary:

import csv

with open('all16.csv', 'r', newline='') as file:
    has_header = csv.Sniffer().has_header(file.read(1024))
    file.seek(0)  # Rewind.
    reader = csv.reader(file)
    if has_header:
        next(reader)  # Skip header row.
    column = 1
    datatype = float
    data = (datatype(row[column]) for row in reader)
    least_value = min(data)

print(least_value)

由于在您的示例中datatype和column是硬编码的，因此像这样处理row会稍微快一些:

Since datatype and column are hardcoded in your example, it would be slightly faster to process the row like this:

    data = (float(row[1]) for row in reader)

注意:上面的代码适用于Python3.x.对于Python 2.x，请使用以下行来打开文件，而不是显示的内容:

Note: the code above is for Python 3.x. For Python 2.x use the following line to open the file instead of what is shown:

with open('all16.csv', 'rb') as file:

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