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* Improve Filter Syntax documentaion / navigation * update links and missing diagrams * rename legacy prefix to shortcut prefix * Update editions/tw5.com/tiddlers/filters/Filter Operators.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/And Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Cascade Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/And Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * add most changes a suggested by yaisog * fix copy / paste from-version * replace operand with parameter in the docs * fix typo * fix typos and improve railroad diagrams consistency * move "new from version" info for filter run prefixes below the table * fix typo transclusion and substitution * Move Filters tiddler to the top level in the TOC * wip-breadcrumbs * breadcrumbs & breadcrumbsList macro final * remove files that do not belong to this PR * restore release banner * add simple / story mode to breadcrumbs * .breadcrumbs macro update comments * new breadcrumbs CSS, woks with small screens * make CSS configurable using hidden-settings * improve CSS fro small screens * remove the initial: recursiveParentTag macro * improve location info for breadcrumbs nav. add "alt-text" for Edge ::after element * breadcrumbs add mode=field * bc add initial docs * breadcrumbsField will also respect the story ordering * add configurable global filterMode setting * improve arrow CSS for browser zooming * add bc links use bc-caption if caption field is non-empty * breadcrumbs improve comments * breadcrumbs aria-lable uses caption if there is one * breadcrumbs improve documentation * breadcrumbs improve docs for sort param * fix showArrows docs * remove .bc-link aria-label .. it's not needed if caption is resolved properly * use subfilter instead of enlist to evaluate the "excluded" variable. Be consistent with toc-macros * remove breadcrumbs macros - they have their own PR now * resolve conflict * add back doc-macros tiddler * integrate :then filter run prefix * remove .breadcrumbs macros and their config tiddlers * fix typos as requested --------- Co-authored-by: yaisog <m@rcuswinter.de>
60 lines
4.5 KiB
Plaintext
60 lines
4.5 KiB
Plaintext
created: 20210618134753828
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modified: 20230305125405422
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tags: [[Map Filter Run Prefix]]
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title: Map Filter Run Prefix (Examples)
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type: text/vnd.tiddlywiki
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Replace the input titles with the caption field if it exists, otherwise preserve the input title:
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<<.operator-example 1 "[tag[Widgets]] :map[get[caption]else{!!title}]">>
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<<.tip "The above example is equivalent to `[tag[Widgets]] :map[{!!caption}!is[blank]else{!!title}]`. Note that referencing a field as a text reference such as `{!!caption}` returns an empty string for a non-existent or empty caption field. Therefore a check for `is[blank]` is needed before the `else` operator">>
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For each title in a shopping list, calculate the total cost of purchasing each item:
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<<.operator-example 2 "[tag[shopping]] :map[get[quantity]else[0]multiply{!!price}]">>
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Get the tags of all tiddlers tagged `Widget:`
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<<.operator-example 3 "[tag[Widgets]] :map:flat[tagging[]] :and[!is[blank]unique[]]">>
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<<.tip "Without the `flat` suffix the `:map` filter run only returns the first result for each input title">>
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!! Comparison between `:map` with and without the `flat` suffix
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The `:map` filter run will return at least as many outputs as given in the input. By default one input item will result in exactly one output item. When the filter run transforms an input item into an empty result, the output for that item will be an empty string. When the filter run transforms an input item into multiple items, only the first item will appear in the output. This behavior can be overridden by providing the `flat` suffix. The `flat` suffix will cause all the items to appear in the output.
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| `:map` | `:map:flat` |
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|^<<.operator-example m0.1 "[range[4]] :map[match[this matches nothing]]">>|^<<.operator-example m0.2 "[range[4]] :map:flat[match[this matches nothing]]">>|
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|^<<.operator-example m1.1 "[range[4]] :map[range<currentTiddler>]">>|^<<.operator-example m1.2 "[range[4]] :map:flat[range<currentTiddler>]">>|
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|^<<.operator-example m2.1 "[range[4]] :map[range<currentTiddler>]">>|^<<.operator-example m2.2 "[range[4]] :map:flat[range<currentTiddler>first[]]">>|
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|^<<.operator-example m3.1 "[range[4]] :map[range<currentTiddler>sum[]]">>|^<<.operator-example m3.2 "[range[4]] :map:flat[range<currentTiddler>sum[]]">>|
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|^<<.operator-example m4.1 "[[1,2,3]] [[4,5]] :map[split[,]]">>|^<<.operator-example m4.2 "[[1,2,3]] [[4,5]] :map:flat[split[,]]">>|
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|^<<.operator-example m5.1 "[[1,2,3]] [[4,5]] :map[split[,]]">>|^<<.operator-example m5.2 "[[1,2,3]] [[4,5]] :map:flat[split[,]first[]]">>|
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!! Comparison between `:map` and `:and`/`+` filter run prefixes
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The functionality of the `:map` filter run prefix has some overlap with the `:and` prefix (alias `+`). They will sometimes return the same results as each other. In at least these cases, the results will be different:
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# The `:and` filter run can modify the number of items (either increase or decrease). The `:map` run will never alter the number of items.
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# The number of items in the `:and` filter run will also decrease due to [[de-duplication|Dominant Append]]. The `:map` run will not [[de-duplicate|Dominant Append]].
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# Explicit references to the "currentTiddler" variable will behave differently
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# Implicit references to the "currentTiddler" using TextReference will behave differently.
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| `:map` | `:and` |
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|!results are the same|<|
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|^<<.operator-example 1.1 "[range[5]] :map[add[1]]">>|^<<.operator-example 1.2 "[range[5]] :and[add[1]]">>|
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|^<<.operator-example 2.1 "[range[5]] :map[addsuffix[ hello]]">>|^<<.operator-example 2.2 "[range[5]] :and[addsuffix[ hello]]">>|
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|^<<.operator-example 3.1 "[tag[shopping]] :map[get[quantity]]">>|^<<.operator-example 3.2 "[tag[shopping]] :and[get[quantity]]">>|
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|!decrease in the number of items|<|
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|^<<.operator-example 4.1 "[range[5]] :map[sum[]]">>|^<<.operator-example 4.2 "[range[5]] :and[sum[]]">>|
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|^<<.operator-example 5.1 "[range[5]] :map[join[,]]">>|^<<.operator-example 5.2 "[range[5]] :and[join[,]]">>|
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|!increase in the number of items|<|
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|^<<.operator-example 6.1 "[[1,2,3]] [[4,5]] :map[split[,]]">>|^<<.operator-example 6.2 "[[1,2,3]] [[4,5]] :and[split[,]]">>|
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|!de-duplication|<|
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|^<<.operator-example 7.1 "[range[5]] :map[[hello]]">>|^<<.operator-example 7.2 "[range[5]] :and[[hello]]">>|
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|!currentTiddler|<|
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|^<<.operator-example 8.1 "[tag[shopping]] :map[<currentTiddler>]">>|^<<.operator-example 8.2 "[tag[shopping]] :and[<currentTiddler>]">>|
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|^<<.operator-example 9.1 "[tag[shopping]] :map[{!!quantity}]">>|^<<.operator-example 9.2 "[tag[shopping]] :and[{!!quantity}]">>|
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