C#Groupby，然后在分割CSV之后求和(无标题) [英] C# Groupby then Sum after Split CSV (no Headers)

问题描述

阅读过各种文章之后，我认为我已经接近想要的结果了，但是求和"部分给出了错误的答案.我怀疑是由于我的csv文件没有列标题而导致的，因为我称之为"sum".

Having read the various post, I think I'm close to getting the result I want but the "sum" part is giving the wrong answer. I suspect its due to the way I call the "sum" as my csv file does not have column headers.

csv文件包含以下内容:

csv file contains the following:

222，1

222, 1

223，2

222，1

224，2

222，-1

我想要做的是

• 读取CSV文件并拆分数据
• 按第一列分组
• 按组汇总第二列

这是我到目前为止所做的:

Here is what I have done so far:

var newquery = from line in File.ReadAllLines(path_source) //read all lines in csv file
                       let values = line.Split(',') //split the values by separator
                       let price_value = values[0]                                                      
                       group line by price_value into g                           
                       orderby g.Key
                       //select g;
                       select new 
                       {
                           price_column = g.Key,
                           qty_column = g.Sum(x => x[1]) 
                       };

var writesum = newquery.Select(record => record.price_column + "," + record.qty_column);

File.WriteAllLines(path_target, writesum);

path_target文件显示:

The path_target file shows:

222，45

222, 45

223，80

224、65

这告诉我split，groupby，orderby语法正确，但是sum完全错误.

This tells me that the split, groupby, orderby syntax is correct but the sum is totally wrong.

我怀疑sum结果错误的原因之一是由于qty_column = g.Sum(x => x[1])的语法.

I suspect one of the reasons the results for the sum is wrong is due to the syntax here qty_column = g.Sum(x => x[1]).

由于我的数据不包含标头，因此无法像示例中那样调用x.something.

As my data does not contain headers, I'm not able to call x.something as in the examples.

另一方面，在这一点上我可能是完全错误的！

On the other hand I could be totally wrong on this point!

非常感谢您的帮助.

推荐答案

首先，将值拆分后进行分组，而不是原始行:

First of all, group the values after they are splitted, not the raw line:

group values by price_value into g

代替

group line by price_value into g

在对它们求和之前，下一步将要求和的string解析为ints:

Next parse the string you want to sum as ints before you sum them:

qty_column = g.Sum(x => int.Parse(x[1]))

代替

qty_column = g.Sum(x => x[1])

因为x[1]是string.

现在的结果是:

var newquery = from line in File.ReadAllLines(path_source) //read all lines in csv file.
                       let values = line.Split(',') //split the values by separator
                       let price_value = values[0]
                       group values by price_value into g
                       orderby g.Key
                       //select g;
                       select new
                       {
                           price_column = g.Key,
                           qty_column = g.Sum(x => int.Parse(x[1]))
                       };

哪个给您:

222，1

222, 1

223，2

224，2

无论如何，流利的语法将更具可读性:

Anyway, fluent syntax will be somewhat more readable:

var v = new List<string> File.ReadAllLines(path_source) //read all lines in csv file.
    .Select(x => x.Split(','))
    .Select(x => new { Key = x.First(), Value = x.Last() })
    .GroupBy(x => x.Key)
    .Select(x => new
    {
        price_column = x.Key,
        qty_column = x.Sum(y => int.Parse(y.Value))
    });

这篇关于C#Groupby，然后在分割CSV之后求和(无标题)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！