Eventually managed to compute the intersection of two filters outputs !

[Eric N.]

I was stuck in my dev because I couldn't output the intersection of two filters, each made of several runs. I didn't find a built-in function to do so, and I couldn't find a satisfying solution online. But I eventually found my own solution, shared here.

Say I want to get all the tiddlers that satisfy the following conditions (toy example here, could also have a pair of very complex filters):

(has tag Todo OR starts with "a") AND (has tag Howto OR starts with "al")

This is computed by the following code, where the output list is enlist<setAinterB>, which is displayed by the list-links macro.

<$set name="filterA" filter="[tag[Todo]] [all[]prefix[a]]">

<$set name="filterB" filter="[tag[Howto]] [all[]prefix[al]]">

<$set name="setAunionB" filter="[enlist<filterA>] [enlist<filterB>]">

<$set name="setAnotB" filter="[enlist<filterA>] -[enlist<filterB>]">

<$set name="setBnotA" filter="[enlist<filterB>] -[enlist<filterA>]">

<$set name="setAinterB" filter="[enlist<setAunionB>] -[enlist<setAnotB>] -[enlist<setBnotA>]">

<<list-links "[enlist<setAinterB>sort[]]">>

</$set>

</$set>

</$set>

</$set>

</$set>

Caveat : if a filter output contains double brackets (say a tiddler named "oh what a [[bad]] name") it breaks the enlist processing, and you won't have the correct output.

Best,

Eric

[Mohammad]

Hi Eric,

 Thank you for sharing!

 Looking in TW-Scripts you can find two great resources for working with filters:

• Jed Carty: https://ooktech.com/jed/ExampleWikis/FilterLogicExamples/
• Tobias Beer: https://tobibeer.github.io/tw/filters/#Filter%20Examples

 

and I alos would like to add the great interactive playground by Eric Shulman

http://tiddlytools.com/filtergenerators.html

These are three wonderful sources for learning filters and of course the holly TW-Scripts :-) :-)

--Mohammad

[A Gloom]

Mohammad

you need to make a filters reference tiddler at TWScripts (if you hadn't already) containing the following info you posted here (and belopw)

 

• Jed Carty: https://ooktech.com/jed/ExampleWikis/FilterLogicExamples/
• Tobias Beer: https://tobibeer.github.io/tw/filters/#Filter%20Examples

and I alos would like to add the great interactive playground by Eric Shulman

http://tiddlytools.com/filtergenerators.html

These are three wonderful sources for learning filters and of course the holly **TW-Scripts**

**  link to a tiddler with a list of all TWScripts filter info tiddlers

[Eric N.]

Thanks Mohammad, I'll check it out !

[TonyM]

Eric N

Thanks for sharing, I thought I would turn it into a macro because it is a general type of solution.

\define intersect(filter1 filter2)
<$set name="filterA" filter="$filter1$">
<$set name="filterB" filter="$filter2$">

<$set name="setAunionB" filter="[enlist<filterA>] [enlist<filterB>]">
<$set name="setAnotB" filter="[enlist<filterA>] -[enlist<filterB>]">
<$set name="setBnotA" filter="[enlist<filterB>] -[enlist<filterA>]">
<$set name="setAinterB" filter="[enlist<setAunionB>] -[enlist<setAnotB>] -[enlist<setBnotA>]">
<<list-links "[enlist<setAinterB>sort[]]">>
</$set></$set></$set></$set></$set>

\end

<<intersect "[tag[Todo]] [all[]prefix[a]]" "[tag[Howto]] [all[]prefix[al]]">>

But I avoid the list-links macro because its a fixed format

The following lists only tiddler titles, using the default list widget behaviour, but it easy to present things differentl

\define intersect(filter1 filter2)
<$set name="filterA" filter="$filter1$">
<$set name="filterB" filter="$filter2$">

<$set name="setAunionB" filter="[enlist<filterA>] [enlist<filterB>]">
<$set name="setAnotB" filter="[enlist<filterA>] -[enlist<filterB>]">
<$set name="setBnotA" filter="[enlist<filterB>] -[enlist<filterA>]">
<$set name="setAinterB" filter="[enlist<setAunionB>] -[enlist<setAnotB>] -[enlist<setBnotA>]">

<$list filter="[enlist<setAinterB>sort[]]">

</$list>
</$set></$set></$set></$set></$set>
\end

For example place this in the blank line above

  <$link/>,

or you could add another parameter and use this template

\define intersect(filter1 filter2 template:"defaulttemplate")
<$set name="filterA" filter="$filter1$">
<$set name="filterB" filter="$filter2$">

<$set name="setAunionB" filter="[enlist<filterA>] [enlist<filterB>]">
<$set name="setAnotB" filter="[enlist<filterA>] -[enlist<filterB>]">
<$set name="setBnotA" filter="[enlist<filterB>] -[enlist<filterA>]">
<$set name="setAinterB" filter="[enlist<setAunionB>] -[enlist<setAnotB>] -[enlist<setBnotA>]">

<$list filter="[enlist<setAinterB>sort[]]" template="$template$">

</$list>

</$set></$set></$set></$set></$set>

\end

Enjoy the possibilities

Regards

Tony

[Eric N.]

Thanks TonyM that's very handy !

Would you know if there is a way to return the intersection set as a variable for later reuse ?

Then I wouldn't have to decide upfront what to do with the intersection in the macro.

I mean something like:

f=intersect("[tag[Todo]] [all[]prefix[a]]", "[tag[Howto]] [all[]prefix[al]]")

<<list-links "[enlist< $f$ >sort[]]">>

<$list filter="[enlist<setAinterB>sort[]]"

>
<$link/>
</$list>

...

But with the proper way to use variables, functions, macros, parameters, .... (what these elements are and how to use them in different contextes is still unclear to me)

Cheers !

[Mohammad]

Hi A Gloom,

 They are listed in TW-Scripts! But as you said I will create a tiddler references all of them.

[A Gloom]

Mohammad

 

 They are listed in TW-Scripts! But as you said I will create a tiddler references all of them.

Excellent-- you have so much content now-- having summary/quick reference tiddlers may keep ppl from getting overwhelmed by search results in TWScripts-- I used the idea Tobias' Solutions index page had-- each topic tag had an index page.

[TonyM]

Eric,

You need to wikify the result of a complex macro before feeding it into the next widget otherwise the macro code is included.

• One way to conceptualise this is;
• tiddlywiki always tries and passes the un-wikified result along so it can be "evaluated" at the last moment
• Use the wikify at the last minute or in the wikitext that is using the result. Unfortunately you can't move the wikify widget into a macro
• because it too will not be evaluated
• Remember - If you supply a complex macro  rather than a simple variable to a widget as a parameter it is like saying
  Evaluate the widget, no wait first Evaluate the Parameter then evaluate the widget. See second example below
• If First you wikify it it becomes a simple variable with the result as already evaluated so looks more like a simple variable. 

;Macro Result

<<intersect "[tag[Todo]] [all[]prefix[a]]" "[tag[Howto]] [all[]prefix[al]]">>

<hr>

;Macro used as input to the text widget
<$text text=<<intersect "[tag[Todo]] [all[]prefix[a]]" "[tag[Howto]] [all[]prefix[al]]">>/>
<hr>

;Use as Variable after wikifying
<$wikify name=result text="""<<intersect "[tag[Todo]] [all[]prefix[a]]" "[tag[Howto]] [all[]prefix[al]]">>""" >
<$text text=<<result>>/>
</$wikify>

Regards

Tony

[Eric N.]

Tony,

That was very helpful !!

As my intent is to use the result in a list widget, I went with 

1/ returning this in the macro :

<$list filter="[enlist<setAinterB>sort[]]">

  <$text text="[["/>{{!!title}}<$text text="]]"/>

</$list>

2/ storing the result with wikify :

<$wikify name=result text="""<<intersect "[tag[Todo]] [all[]prefix[a]]" "[tag[Howto]] [all[]prefix[al]]">>""" >

3/ using the result in various ways :

<<result>>

<$text text=<<result>>/>

and in a list, my initial intent:

<$list filter=<<result>> >

;{{!!title}}

:{{!!tags}}

</$list>

Works perfectly, thanks again ! 

Eric N.

[TonyM]

And eventually close the wikify </$wikify>

good stuff thanks for sharing your original work

Tony