# Changing Family Based on Parameter Value **URL:** \ **Category:** Uncategorized\ **Created:** [November 1, 2017, 2:07pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147 "2017-11-01T14:07:05Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![robertsb2010](https://avatars.discourse-cdn.com/v4/letter/r/7c8e57/32.png) [@robertsb2010](https://forum.dynamobim.com/u/robertsb2010)\ **Post date:** [November 1, 2017, 2:07pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/1 "2017-11-01T14:07:05Z")
Hey everyone, I need some help. I have been trying to find a way to change a family type based on a parameter value and I am having trouble. In this script, I find the “specified supply airflow” and then divide it among all diffusers in a space. I’d like to give cfm ranges and automatically have the family change to the correct type based on what range it falls in. I was thinking the “if” node, but can’t seem to get it to function how I’d like. Any help is appreciated. I’ve attached the dynamo file and a screenshot. ![Capture](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/8/f/8f3a585ec06eee5a7456cf5ae3d1b733a35a7963.PNG) [Apply CFM across ATs.dyn](https://forum.dynamobim.com/uploads/short-url/eboLGAc4y6ILqmGjQB9xwrn0qSt.dyn) (21.8 KB) ---
**Author:** ![Ewan\_Opie](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ewan_opie/32/77070_2.png) [@Ewan\_Opie](https://forum.dynamobim.com/u/Ewan_Opie)\ **Post date:** [November 1, 2017, 9:19pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/2 "2017-11-01T21:19:41Z")
If it is a numerical range or number you are using to define the inputs, then this may work for you. ![Multiple Inputs](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/9/6/961791f4ba56be345eb3a53a68ff995f739a17b9.gif) ---
**Author:** ![robertsb2010](https://avatars.discourse-cdn.com/v4/letter/r/7c8e57/32.png) [@robertsb2010](https://forum.dynamobim.com/u/robertsb2010)\ **Post date:** [November 2, 2017, 1:19pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/3 "2017-11-02T13:19:02Z")
Thanks for the response! I’m going to try this out and see if it gets me where I want to be. UPDATE: When I try this, it runs without error, but doesn’t change any families inside the revit file. ---
**Author:** ![Ewan\_Opie](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ewan_opie/32/77070_2.png) [@Ewan\_Opie](https://forum.dynamobim.com/u/Ewan_Opie)\ **Post date:** [November 2, 2017, 9:33pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/4 "2017-11-02T21:33:38Z")
I have shown Strings as inputs/outputs. Are you feeding actual family types into the inputs? ![ezgif-3-17989dfac9](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/f/7/f7201e2ed6c6e3510d287d1f72420fd0b9ebf345.gif) ---
**Author:** ![robertsb2010](https://avatars.discourse-cdn.com/v4/letter/r/7c8e57/32.png) [@robertsb2010](https://forum.dynamobim.com/u/robertsb2010)\ **Post date:** [November 3, 2017, 3:03pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/5 "2017-11-03T15:03:56Z")
That’s what I tried. That’s the end goal is to select actual families based on parameter values that are pulled from the revit file. The entire script reads “specified supply airflow” of a space and divides that among all the diffusers it finds within a space. I would like to take the divided values and auto pick a family based on a given cfm range (i.e. select Family 1 if cfm is between 0-120 cfm, etc.) Also, could you elaborate a little on what exactly that code block is doing? I get the general idea, but I’m a little inexperienced with code blocks. ---
**Author:** ![Ewan\_Opie](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ewan_opie/32/77070_2.png) [@Ewan\_Opie](https://forum.dynamobim.com/u/Ewan_Opie)\ **Post date:** [November 3, 2017, 9:45pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/6 "2017-11-03T21:45:26Z")
All good. I am out of the office for a couple of days. I’ll get something on range input posted when I get back as I also have an idea on how to do this with OOTB nodes. Unless there are any other ideas from the forum? Python gurus? 😉 ---
**Author:** ![Yna\_Db](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/yna_db/32/30641_2.png) [@Yna\_Db](https://forum.dynamobim.com/u/Yna_Db)\ **Post date:** [November 3, 2017, 10:00pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/7 "2017-11-03T22:00:49Z")
> [@robertsb2010](#): > > what exactly that code block is doing? That code block holds a conditional statement (similar function as an _if_ node), see here: [http://dynamoprimer.com/en/07\_Code-Block/7-3\_shorthand.html](http://dynamoprimer.com/en/07_Code-Block/7-3_shorthand.html) This conversation could also bring additional clues: > [@Replacing a number of selected elements with another family type keeping original dimensions](https://forum.dynamobim.com/t/replacing-a-number-of-selected-elements-with-another-family-type-keeping-original-dimensions/8315/2): > ---
**Author:** ![Ewan\_Opie](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ewan_opie/32/77070_2.png) [@Ewan\_Opie](https://forum.dynamobim.com/u/Ewan_Opie)\ **Post date:** [November 4, 2017, 5:10am UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/8 "2017-11-04T05:10:46Z")
Righto, I knew I had seen something like this before. I’ve just typed this out on my phone but it should be able to be adapted for your purpose @robertsb2010 Example: X=input list of values a=family type 1 for values 0 to 100 b=family type 2 for values 101 to 200 c=family type 3 for values 201 to 300 d=family type 4 for values 3011 to 400 The code block contents: ``` x>=0&&x<=100 ? a: x>=101&&x<=200 ? b: x>=201&&x<=300 ? c: x>=301&&x<=400 ? d: "Out of range"; ``` The inspiration: > [@If ( then , else) in dynamo](https://forum.dynamobim.com/t/if-then-else-in-dynamo/2556/6): > > Konrad, Michael, Many thanks. Managed to make it work! And the code block processes a list of 100+ values in seconds, when some of the monstrosities I’ve built out of nodes took ages! Just goes to show the inherent inefficiency of visual programming I guess. The end result looks like this: [Capture3]                   Best Regards. I’ll still see if my OOTB node solution idea works on Monday. 🙂 ---
**Author:** ![Ewan\_Opie](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/ewan_opie/32/77070_2.png) [@Ewan\_Opie](https://forum.dynamobim.com/u/Ewan_Opie)\ **Post date:** [November 6, 2017, 9:59pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/9 "2017-11-06T21:59:36Z")
Here is an example of the Code Block in action as well as my OOTB Node workflow. Please let me know if this solves your problem @robertsb2010 😀 Animation: ![Multiple Inputs OOTB](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/9/b/9b6a905a863be326dc920812e498d627e5ae9272.gif) Screengrab: ![OOTB and Code Multiple If Ranges](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/6/4/6495dba79c4cd86e52e2fd39588c0b923907c0b0.png) ---
**Author:** ![robertsb2010](https://avatars.discourse-cdn.com/v4/letter/r/7c8e57/32.png) [@robertsb2010](https://forum.dynamobim.com/u/robertsb2010)\ **Post date:** [November 7, 2017, 1:58pm UTC](https://forum.dynamobim.com/t/changing-family-based-on-parameter-value/16147/10 "2017-11-07T13:58:16Z")
Wow, that code block is nice! I got it to work after toying with the code block contents a little bit. I was definitely confused by the code block workflow at first. Also, I had to convert my list to ft3/sec as Dynamo doesn’t actually read cfm the way that Revit does. That wasn’t hard to do at all, just another step. Thanks for everyone’s replies!