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(twine2.1.3 harlowe 2.0.1)

The harlowe documentation states "The subset can be based on each string's characters, each datamap's values." But how can datamaps be used with find: while still retaining context?

in an other question a datamap with a collection "boxes" with different values is created.

(set: $boxes to (datamap: "green" , 0 , "blue" , 0 , "red" , 0 , "purple" , 0 , "yellow" , 0 , "neon paisley" , 0))
(set: $marbles to 12)
(for: each _drop , ...(range: 1 , $marbles))[
	(set: $boxes's (either: ...(datanames: $boxes)) to it + 1)
	]

I've been using (for:) loops to check the values of each item to see if they match a condition, but this seems expensive, large datamaps cause a noticeable lag for the browser to display the passage. The for loops can also be quite complicated. This seems to be exactly what (find:) is for.

But I'm having trouble using (find:) to check the values in a way which identifies the boxes. I think it may be an issue of combining the proper syntax into the find:.

This

(find: _some where _some is > 0, ...(datavalues: $boxes))

Gives a list of contents > 0 but doesn't identify the box. Makes sense since it's an array of numbers being evaluated. It's also useless, an array of numbers with no context.

Likewise,

(find: _check where _check is not "frog" , ...(datanames: $boxes))

gives a list of the names

But I've found no way to combine the two together which provides names and numbers (effectively making a temporary datamap for display).

(for: each _name , ...(datanames: $boxes))[
	(if: (_name of $boxes) is > 0)[
		_name has (print: (_name of $boxes))]
]

or

{(set: $secondDatamap to (datamap:))
(for: each _name , ...(Datanames: $boxes))[
	(if: (_name of $boxes) is > 0)[
	(set: $secondDatamap to it + (datamap: _name , (_name of $boxes)))
	]
]}
$secondDatamap

seem to be the best method(s).

Am I completely misunderstanding the purpose of find: (this is quite likely!)?

Is there a better way to evaluate and return the values of a datamap while keeping it in context of the value's name? (while using harlowe macros, avoiding java)

1 Answer

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Best answer

notes:

1. When using a mathematical comparison operator like > (greater-than) it is best not to also include an is keyword operator, especially when using mathematical operators like >= (greater-than-or-equal-to). Harlowe 2.x was changed to support using is before mathematical operator to better support syntax errors some Author's were making.

Correct: (if: $var > 0 or $var <= 20)[...some code...]

Now supported: (if: $var is > 0 or $var is <= 20)[...some code...]

1. The programming language used by web-browsers is Javascript, not Java, which is a totally unrelated language with an unfortunately similar name.

 

The documentation for the (find:) macro clearly states it searches through values, so it is not the macro you want and unfortunately the only other one you can use is the (for:) macro.

As far as I remember there is also no standard Javascript function to do what you want either, the closest would be the <Array>.map() function but that is for an Array and not a Map object (which is what (datamap:) is using) so you would need to do a for-loop in Javascript similar to what you're doing with TwineScript anyway.

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