在python中求和一个csv列
- 作者: 开门--查水表
- 来源: 51数据库
- 2022-10-21
问题描述
我正在尝试对 csv 文件中的一列求和.该文件如下所示:
I'm trying to make a sum of a column in a csv file. The file looks like:
Date Value 2012-11-20 12 2012-11-21 10 2012-11-22 3
这可以在数百行的范围内.我需要将总价值(在本例中为 25)打印到终端上.到目前为止,我有一些代码,但它导致的数字比它应该总和要小得多.在对其进行故障排除时,我打印了总和,并意识到它实际上不是将 12 + 10 + 3 相加,而是将每列中的数字和总和为 1 + 2 + 1 + 0 + 3,这显然等于很多较小的总数.这是我的代码,如果有人可以提出建议会很棒!
This can be in the range of hundreds of rows. I need to get the total of Value (in this case it would be 25) printed on to a terminal. I so far have some code but it's resulting in a much smaller figure than it should sum. When troubleshooting it, I did a print of the sum and realized that instead of summing 12 + 10 + 3, it actually breaks the numbers in each column and sums as 1 + 2 + 1 + 0 + 3, which obviously equals to a much smaller total. Here's my code, if someone could make a recommendation would be great!
with open("file.csv")) as fin: headerline = fin.next() total = 0 for row in csv.reader(fin): print col # for troubleshooting for col in row[1]: total += int(col) print total
推荐答案
csv 模块会逐行循环,无需再循环遍历列.只求和 int(row[1]):
The csv module loops over your rows one by one, there is no need to then loop over the column. Just sum int(row[1]):
with open("file.csv") as fin: headerline = fin.next() total = 0 for row in csv.reader(fin): total += int(row[1]) print total
您可以使用带有生成器表达式和 sum() 内置函数的快捷方式:
You can use a shortcut with a generator expression and the sum() built-in function:
with open("file.csv") as fin: fin.next() total = sum(int(r[1]) for r in csv.reader(fin))
请注意,在 Python 中,字符串也是序列,因此当您执行 for col in row[1]: 时,您将遍历 row[1];所以对于你的第一行是 1 和 2:
Note that in Python, strings are sequences too, so when you do for col in row[1]: you are looping over the individual characters of row[1]; so for your first row that'd be 1 and 2:
>>> for c in '123': ... print repr(c) ... '1' '2' '3'