List Index Bug

Replies to This Discussion

Permalink Reply by David Rutten on March 1, 2011 at 9:02am

Hi John,

 

forget List Index, it doesn't do what you think it does.

 

Try the following. Sort an array of index numbers in parallel with the values, the first item represents the lowest index, the last item the highest index:

 

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David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Danny Boyes on March 1, 2011 at 9:07am

It's not a bug. You need to compare like for like for the Item Index to work. In this example I've got a method for finding the maximum value to find in the list (which fails) and the Actual Item itself to find in the list which is 23.

The difference between this and the Sorted method you used is the Actual list output rather than the K values.

 

EDIT: Or go with David's

Permalink Reply by Danny Boyes on March 1, 2011 at 11:06am

As far as I know it, a good metaphor to describe the Item Index component is this:

I have a List of People. For Example John Baker, Danny Boyes, David Rutten.

I want the Item Index of me, Danny Boyes, so I ask the component to compare my name with the List of People and it fails. The words Danny Boyes does not equal the flesh and bones that is me. What I should have asked the component to compare was me, the person, in order to find the index of me.

This is why finding the value 99.0 for the max value in the above example fails because the value is not the item. 

Permalink Reply by David Rutten on March 1, 2011 at 11:42am

Exactly, a somewhat more hard-core but less abstract explanation is the List Index doesn't look at the actual value. It only looks at the memory-address where that value is stored. So if you have two equal numbers, they can either be stored in two different spots in RAM, or they actually both 'point' to the same spot. List Index will at present only find the latter kind of similarity.

 

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David Rutten

david@mcneel.com

Poprad, Slovakia