mirror of
https://github.com/Jermolene/TiddlyWiki5
synced 2024-07-01 09:43:16 +00:00
f60d0ef109
Fixes #5246. Now the reduce operator and :reduce filter run prefix will both return empty output when their input is empty, so that both can be chained together with the else operator or :else prefix.
39 lines
1.7 KiB
Plaintext
39 lines
1.7 KiB
Plaintext
created: 20201004154413968
|
|
modified: 20201204131137081
|
|
tags: [[Operator Examples]] [[reduce Operator]]
|
|
title: reduce Operator (Examples)
|
|
type: text/vnd.tiddlywiki
|
|
|
|
\define add-price() [get[price]multiply{!!quantity}add<accumulator>]
|
|
\define num-items() [get[quantity]add<accumulator>]
|
|
\define join-with-commas() [<index>compare:number:gt[0]then<accumulator>addsuffix[, ]addsuffix<currentTiddler>else<currentTiddler>]
|
|
\define multiply-input() [multiply<accumulator>]
|
|
\define display-variable(name)
|
|
''<$text text=<<__name__>>/>'': <code><$text text={{{ [<__name__>getvariable[]] }}}/></code>
|
|
\end
|
|
|
|
These examples use the following predefined variables:
|
|
|
|
* <<display-variable add-price>>
|
|
* <<display-variable num-items>>
|
|
* <<display-variable join-with-commas>>
|
|
* <<display-variable multiply-input>>
|
|
|
|
They also use the following data tiddlers:
|
|
|
|
<ul>
|
|
<$list filter="[tag[shopping]!has[draft.of]]">
|
|
<li>
|
|
''<$link><$text text=<<currentTiddler>>/></$link>'' quantity: <$text text={{!!quantity}}/>, price: <$text text={{!!price}}/>
|
|
</li>
|
|
</$list>
|
|
</ul>
|
|
|
|
<<.operator-example 1 "[tag[shopping]reduce<num-items>]">>
|
|
<<.operator-example 2 "[tag[shopping]reduce<add-price>]">>
|
|
<<.operator-example 3 "[tag[shopping]reduce<join-with-commas>]" "Uses `<index>` to act differently on the first item than the rest">>
|
|
<<.operator-example 4 "[tag[non-existent]reduce<add-price>]" "Empty input produces empty output">>
|
|
<<.operator-example 5 "[tag[non-existent]reduce<add-price>else[0]]" "Use `else` to ensure output if input was empty">>
|
|
<<.operator-example 6 "=1 =2 =3 +[reduce<multiply-input>]" "Empty initial value is treated as 0 by mathematical operators">>
|
|
<<.operator-example 7 "=1 =2 =3 +[reduce<multiply-input>,[1]]" "Setting initial value is sometimes necessary for correct results">>
|