Spotfire：过滤表以从每个组中获取一条记录

Question

I have the following table:

UWI	FORM	SOURCE	MD
123	BRAIDED	DRR	100
123	BRAIDED	ERK	150
123	BRAIDED	KPB	200
123	TUSCHER	DRR	300
123	TUSCHER	MDB	350
123	TUSCHER	KPB	375
456	BRAIDED	DRR	150
456	BRAIDED	KPB	275
456	TUSCHER	BTM	500
456	TUSCHER	DRR	550
456	TUSCHER	ERK	525

All columns are string columns except MD, which is Real, however no math is required.

I need to filter the data so that only one row for a particular UWI and formation are returned based on a set hierarchy of the SOURCE.

The hierarchy is:

1. ERK
2. MDB
3. DRR
4. KPB
5. BTM

What I'm looking for is a table that looks like this once the filter is applied:

UWI	FORM	SOURCE	MD
123	BRAIDED	ERK	150
123	TUSCHER	MDB	350
456	BRAIDED	DRR	150
456	TUSCHER	ERK	525

What is the best way to accomplish this? I thought about adding a DenseRank calculated column, which will group the rows by UWI and FORM using SOURCE for the ranking, but there are two problems with that:

• I don't know how to assign a particular rank number to a particular source; and
• If I take the resulting ranking based on the alphabet, if I add a new source (let's say KMP just under ERK) it will mess up some of the other ranking numbers.

I've thought of using a Case statement, but I'm not sure how to group the UWI and FORM (I know about OVER, but every example I've found requires some kind of number column to do an aggregation).

This filter will be applied just after import.

Any direction would be greatly appreciated!

Answer 1

I received an answer from the Tibco community on how to do this:

On top menu:

Data > Column Properties > select SOURCE

Choose Sort Order tab.

Choose Custom Sort Order and configure the desired order

press OK

Now define the calculated column [SourceRank] as

DenseRank([SOURCE],Concatenate([FORM],[UWI]))

The filter can then be applied to [SourceRank]=1.