c# - What does it mean to filter a collection 'vertically' and 'horizontally'? -

In the required C # 3.0 book, there is a part where it says:

" Projection is very powerful by using the selection method. We have already seen how to filter vertical (decreasing the number of items in the archive) using the standard query operator (.) Select standard query operator, we can also minimize the archive horizontally (making less columns). In combination,

Where () and select () means to remove only the pieces of the original collection which is desirable for the current algorithm. "

What does this case mean horizontally and vertically? Are these methods calculated differently on any collection?

No, they tell the collection equally.

If you think of a collection as a group of objects (rows), then with each of the properties (columns) such as the database table. You can filter results by removing some rows ( vertical ) by specifying a condition using where , or by select ing by column A set can remove a subset of properties ( horizontally ).