C# Linq：选择 List<string> 中的位置
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Linq: select where in List<string>
提问by stefjnl
Struggeling with some LinqToExcel filtering here...
在这里挣扎一些 LinqToExcel 过滤......
Ive got a List<string> columnsToFilterthat contains 9 strings, and with that i want to filter out the data for certain columns in a List<Row>, where Rowcontains the properties
我有一个List<string> columnsToFilter包含 9 个字符串的，并且我想过滤掉 a 中某些列的数据List<Row>，其中Row包含属性
IEnumerable<string> ColumnNames
Cell this[string columnName]
So: List<Row>has say 30 rows, each having 12 ColumnNames. Now i want to filter that List<Row>using List<string> columnsToFilterso that i end up with a List<Row>of 30 rows and 9ColumnNames.
所以：List<Row>有 30 行，每行有 12 个列名。现在我想筛选List<Row>使用List<string> columnsToFilter，使我有最后List<Row>的30行，9个COLUMNNAMES。
I can select the data for onecolumn by quering the columnname:
我可以通过查询列名来选择一列的数据：
var result = content.Select(m => m["Column1"]).ToList();
Now i want to filter the data based on a Listof strings List<string> columnsToFilter. Whats the best way to achieve that?
现在我想根据字符串列表过滤数据List<string> columnsToFilter。实现这一目标的最佳方法是什么？
采纳答案by stefjnl
I ended up doing this in two steps:
我最终分两步完成：
foreach (var column in columnNumbers)
{
yield return data.Select(m => m[column].Value.ToString()).ToList();
}
Now I have the data I need, but with the rows and columns swapped, so i had to swap rows for columns and vice versa:
现在我有了我需要的数据，但是行和列交换了，所以我不得不交换列的行，反之亦然：
for (int i = 1; i < rowCount; i++)
{
var newRow = new List<string>();
foreach (var cell in list)
{
newRow.Add(cell[i]);
}
yield return newRow;
}
回答by Dweeberly
Is this what you are looking for?
这是你想要的？
var colnames = new List<string>();
var rows = new Dictionary<string, object>();
var result = rows.Where(kv => colnames.Contains(kv.Key)).Select(kv => kv.Value);
回答by Robert Tanenbaum
Define an object called MyObject which has the property names corresponding to the 9 columns that you want to select.
定义一个名为 MyObject 的对象，该对象具有与要选择的 9 列对应的属性名称。
var excel = new ExcelQueryFactory("excelFileName");
var myObjects = from c in excel.Worksheet<MyObject>()
select c;
Bingo. You can now iterate through the 30 objects with the 9 columns as properties. Remember that LinqToExcel will happily fill objects even if they don't have all the columns represented.
答对了。您现在可以使用 9 列作为属性遍历 30 个对象。请记住，即使对象没有表示所有列，LinqToExcel 也会很高兴地填充对象。
You could even have a property or method as part of MyObject called "row" that would be a Dictionary() object so you could say myObject.row["ColumnName"] to reference a value if you preferred that syntax to just saying myObject.ColumnName to get the value. Personally I would rather deal with actual properties than to use the dictionary convolution.
你甚至可以有一个属性或方法作为 MyObject 的一部分，称为“row”，它是一个 Dictionary() 对象，所以你可以说 myObject.row["ColumnName"] 来引用一个值，如果你更喜欢这种语法而不是仅仅说 myObject。 ColumnName 来获取值。我个人宁愿处理实际属性而不是使用字典卷积。
