LINQ GroupBy Sum/Max Assist

[beantownace]

Hello all,

Need an assist on this one to get a clean LINQ C# group. Here is what I am trying to do.

I have a List<Order> orders which has the following fields:
CustomerId
InvoiceDate
SendDate
InvoiceAmount - always positive the transaction type next field determines (-, +)
TransactionType (this will be Buy or Sell)
Comment

What I need is to get a grouped enumerable of the following: (hope this makes sense)

GroupBy (CustomerId, InvoiceDate, SendDate)
Sum(InvoiceAmount) need to handle the Sells as negative and Buys as positive based on the TransactionType
TransactionType (if the sum is positive the TransactionType would be Buy else Sell if negative after sum)
Max (Comment) - only want one value here if they differ across the group records

Thanks all for any assist this one tripping me up.

 

[Skydiver]

Unless you are trying to compete in an obfuscated LINQ, or LINQ code golf contest, why does it have to be written as a single LINQ command? That would obfuscate things rather than make thing clearer about what you are trying to do.

Anyway break down the problem into pieces like you did above. And then take advantage of this overload that lets you customize how the results of each group is made:

Enumerable.GroupBy Method (System.Linq)

Groups the elements of a sequence.

learn.microsoft.com

 

[Skydiver]

Silly question given the following within a particular group:

$5.00, sell
$5.00, sell
$7.00, buy

Is the max supposed to by $5.00 because $5.00 is greater than -$7.00?

Or is the max $7.00 because it has the greatest absolute value?