Intersection of two filter runs

[Mohammad]

I have a code like below

<$vars

 x="1 2 3 4 5"

 y= "2 7 9"

 >

<$list filter="[enlist<x>] +[enlist<y>]" variable=item>

<<item>>

</$list>

 </$vars>

Produces

2 7 9

I expect +run to logically AND the filter output, means those item are in both filter run or the INTERSECTION of two run

e.g. 2

How can I implement this?

--Mohammad

More information

- https://ooktech.com/jed/ExampleWikis/FilterLogicExamples/

- http://tobibeer.github.io/tw/filters/#Filter%20Examples

[Mark S.]

You may not like this version, but it seems to work:

<$vars
 x="1 2 3 4 5"

 y= "2 7 9 3"
f1="[enlist<x>]-[enlist<y>]"
f2="[enlist<y>]-[enlist<x>]"
 >
<$list filter="[enlist<x>] [enlist<y>] -[subfilter<f1>] -[subfilter<f2>]" variable=item>
<<item>>
</$list>
 </$vars>

I worked the logic out with a venn diagram.

I was pleasantly surprised that the <> brackets were interpolated two levels down.

Thanks!

-- Mark

[Mohammad]

Many thanks Mark,

 Yes, it works! I am wondering how can I develop a macro to find the intersection of any two filter runs!

Seems difficult.

--Mohammad

[Mohammad]

Hi again,

 I tried to do something like this

\define intersect-item(filter, item)

<$list filter="[<__item__>] -[subfilter<__filter__>]" variable="result" emptyMessage=<<__item__>> >

</$list>

\end

\define intersect(flt1, flt2)

<$list filter=<<__flt2__>> variable=item >

<$macrocall $name="intersect-item" filter=<<__flt1__>> item=<<item>> />

</$list>

\end

<$vars

 x="7 8 -1 -3 9 11"

 y= "1 2 3 4 5 6 7 8 9"

 >

<$macrocall $name=intersect 

   flt1="[enlist<x>]"

   flt2="[enlist<y>]"

/>

</$vars>

The procedure is, I check every item in filter2 output to see if it is in filter1 output.

If so, I display it, if not, I ignore it!

I am not sure if the code is optimize and according to TW rules and standard.

Application: I have two set of tiddlers, for example those have property1 and those have property2. I want to show 

tiddlers have both properties!

Give me your comments.

--Mohammad


On Wednesday, March 13, 2019 at 10:44:24 PM UTC+3:30, Mark S. wrote:

[Mohammad]

One point:

The Tiddlywiki +run does not necessarily simulate the logical AND operator!

--Mohammad

[Mohammad]

Further input

<$vars

 x="7 8 -1 -3 9 11"

 y= "1 2 3 4 5 6 7 8 9"

 >

<$list filter="[enlist<x>] [enlist<y>] +[sortan[]]">

<<currentTiddler>>

</$list>

The OR logical operator correctly works!

https://tiddlywiki.com/#Filter%20Expression

So, is there a bug in +run filter expression!

--Mohammad

On Wednesday, March 13, 2019 at 8:17:09 PM UTC+3:30, Mohammad wrote:

[Mark S.]

I don't think it qualifies as a true logical operator the way run and -run do. I think of it more of as a funnel > operator, telling the next run to use the previous run as input. I'm not sure that is the same as a true intersection. That's why I did all the extra steps to form the intersection. If the + was a true AND, I wouldn't have had to do that.

-- Mark

[Mohammad]

Thanks Mark!

Just one more question: What is your opinion on the intersection code above?

In real world! In Tiddler Commander I have a filter search to filter some tiddlers based a certain criteria and then I have a checkbox widget to select among those tiddlers!

If I change the filter search (using textbox), I have still the selected tiddlers using checkbox there! So, I need extra step to determine if the

selected tiddlers by checkbox widget are existed in the new filter search. That the reason I have to find intersection.

Thank you again Mark!

--Mohammad

[Mark S.]

Here's a trimmer version of the previous macro. It seems to work and doesn't require calling a macro on each list item:

\define f1() [enlist<x>]-[enlist<y>]
\define f2() [enlist<y>]-[enlist<x>]

<$vars
 x="1 2 3 4 5"

 y= "2 7 9 3"

 >
<$list filter="[enlist<x>] [enlist<y>] -[subfilter<f1>] -[subfilter<f2>]" variable=item>
<<item>>
</$list>
 </$vars>

I think to find out which version is more efficient you'd have to load up a huge array and time the difference. With only a handful of items, the priority is which code is easiest to read and fix later on ?

-- Mark

[Mohammad]

Thanks Mark!

Added to TW-Script.

Cheers

Mohammad