Revitfamily: Formula for an array with correct dimensions

[Marcus.Isacsson]

Hi fellas!

How do I get the family to work as intended? (centrum-centrum 300)
I guess that the formula has to implement some kind of roundup or rounddown for it to be correct?

Thanks in advance! (...in this case we don't want to use repeating detail, this will be a a part of another family)

[barthbradley]

Not sure I understand. Are you Appending Array to End? If so, you can drive the spacing with a labeled dimension to the second component is the Array.  If you are spreading out components to fit (Append to End unchecked), then the spacing is equally divided between all the components  is the Array.  

[Marcus.Isacsson]

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@barthbradley wrote:

Not sure I understand. Are you Appending Array to End? If so, you can drive the spacing with a labeled dimension to the second component is the Array.  If you are spreading out components to fit (Append to End unchecked), then the spacing is equally divided between all the components  is the Array.  

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Yes, it's appending to the end. I want to be able to place a starting point and an ending point so that the array is placed between those points as good as possible according to the centre-centre distance. 

Then I want to set a distance, eg 300 mm between them. A formula should somehow be able to adjust 331 mm to 300 mm and remove one of the objects (if it fixes the distance).

I've used this in a family before but can't seem to find it...

[barthbradley]

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@Marcus.Isacsson wrote:

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Yes, it's appending to the end. I want to be able to place a starting point and an ending point so that the array is placed between those points as good as possible according to the centre-centre distance. 

Then I want to set a distance, eg 300 mm between them. A formula should somehow be able to adjust 331 mm to 300 mm and remove one of the objects (if it fixes the distance).

I've used this in a family before but can't seem to find it...

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By your description, you are NOT Appending to End, but rather placing arrayed components in between the first and last components. 

Also, it sounds like you want the spacing to remain 300 between each component. If so, you're then going to need a Formula for Number of Components in the Array and another Parameter Formula to evaluate it and actually drive the Number of Components in the Array.   

Can you post you file?  

[Avaris. · Accepted solution]

I can't imagine how an array spreading from beginning to end can somehow adjust not to go to the end.

My solution would be to define the second item at a distance (centrum-centrum). Then you can use a formula like:

rounddown(length/(centrum-centrum)) that will give you the correct amount.

[Marcus.Isacsson]

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@barthbradley wrote:

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@Marcus.Isacsson wrote:

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Yes, it's appending to the end. I want to be able to place a starting point and an ending point so that the array is placed between those points as good as possible according to the centre-centre distance. 

Then I want to set a distance, eg 300 mm between them. A formula should somehow be able to adjust 331 mm to 300 mm and remove one of the objects (if it fixes the distance).

I've used this in a family before but can't seem to find it...

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By your description, you are NOT Appending to End, but rather placing arrayed components in between the first and last components. 

Also, it sounds like you want the spacing to remain 300 between each component. If so, you're then going to need a Formula for Number of Components in the Array and another Parameter Formula to evaluate it and actually drive the Number of Components in the Array.   

Can you post you file?  

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I think I solved it by changing "last" to "2nd" for the array and by locking the 2nd component to a reference plane (forgot you could drive the array distance that way)

[barthbradley]

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@Marcus.Isacsson wrote:

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I think I solved it by changing "last" to "2nd" for the array and by locking the 2nd component to a reference plane (forgot you could drive the array distance that way)

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Yes! that's exactly what I told you in my first post. "You can drive the spacing with a labeled dimension to the second component is the Array" with an Append to End.   But, you insisted you weren't doing an Append to End; that you doing it the other way -  which is what I was addressing in my second post (e.g. having a evaluation parameter).   

BTW: you wouldn't need a rounddown parameter if you appended to end. 

Attached:  Append to End Array based on Spacing - No Rounddown Formula Needed.rfa

[Marcus.Isacsson]

@barthbradleyYes, sorry! My bad! Thought it was possible to solve with a formula the other way as well, but I guess not...(?) 🙂
Anyway, thanks for helping out!

[barthbradley · Accepted solution]

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@Marcus.Isacsson wrote:

@barthbradleyYes, sorry! My bad! Thought it was possible to solve with a formula the other way as well, but I guess not...(?) 🙂
Anyway, thanks for helping out!

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It is possible to solve the other way and maintain a determinant spacing interval (e.g. First and Last vs. First and 2nd). I explained that this is would require an evaluation parameter.  If you are arraying between First and Last with a determinate interval, you need to have a secondary length to control the Array in between the start and end point of the line being drawn.  In other words, your pulling 2 lines simultaneously; one that controls the length of the line and the other that places the Array.  For example, if you drawing an array line with arrayed components spaced 2 feet apart on it, then the array will add a component every 2 feet.  Meaning that a 21 foot line will only have 20 feet of components in it.    

See attached example family of an Array to LAST based on determinate spacing.