How to create an new column from ordered pairs

Question

Hi,
Wondering if anyone can help this problem. I am analyzing network traffic between a PC and a Server. I can easily get a count of packets in each direction, PC1 to Server1 and the return path, Server 1 to PC1. But want I really want is a count
of PC1 to OR from Server1, basically a count of packets by IP conversation.
Each row is a packet with fields like: Time, Source, Destination.
For example
2:01:01, PC1, Server1
2:01:01, Server1,  PC1 
I would like to create a new column that represents a conversation. So new have columns: Time, Source, Destination, Conv. To get something like this:
2:01:01, PC1, Server1, Conv1
2:01:01, Server1,  PC1, Conv1
2:01:01, PC2, Server1, Conv2
2:01:01, Server1,  PC2, Conv2
Thanks,
Wes

Answer 1

Wes, I just got around to revisiting your problem. The solution I came up with is twofold. The first part is the creation of a custom function that generates a conversation ID in the form PC1_Server1, PC2_Server1 etc. The second part uses a lookup table
for each unique combination of PC and server to return a conversation number (Conv1, Conv2...).
First of all, the "NetTraffic" table (your original table) generates the following script
let
    Source = Excel.CurrentWorkbook(){[Name="Table8"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Time", type time}}),
in
    #"Changed Type"
In the above, the type of the timestamp column is changed to time, but you can alternatively fix it as text.
I've called the custom function "ConversationIdentifier." It takes four parameters, as described by the parameter names.
(sourceList as list, sourceValue as text, destinationList as list, destinationValue as text) as text=>
let
    SourceConversationList = List.Sort(List.Select(sourceList,each (_ = sourceValue or _ = destinationValue))),
    DestinationConversationList = List.Sort(List.Select(destinationList,each (_ = sourceValue or _ = destinationValue)),Order.Descending),
    ConversationID = SourceConversationList{0}&"_"&DestinationConversationList{0}
in
    ConversationID
Usage:
As an added custom column in Power Query, the formula, based on the "NetTraffic" table would be:
=ConversationIdentifier(#"Changed Type"[Source],[Source],#"Changed Type"[Destination],[Destination])
As previously mentioned, the custom function generates combinations of PC and server, such that each combination represents a conversation.
Next, I created a two-column "ConversationLookup" table in a worksheet, with entries like PC1_Server1|Conv1, PC2_Server1|Conv2, and so on.
In the NetTraffic table, I did a merge with the ConversationLookup table, ensuring that the "Only Include Matching Rows" option is left unchecked (left join).
Finally, I removed unwanted columns. Note: You don't need to use the lookup step if PC1_Server1, PC2_Server1 etc. serves your need for identifying a conversation.