# Projection data in unionizes having 'is\_injection' == True

**URL:** <https://community.brain-map.org/t/projection-data-in-unionizes-having-is-injection-true/2326>\
**Category:** Technical\
**Created:** [May 3, 2023, 1:09pm UTC](https://community.brain-map.org/t/projection-data-in-unionizes-having-is-injection-true/2326 "2023-05-03T13:09:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Pietro](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@Pietro](https://community.brain-map.org/u/Pietro)\
**Post date:** [May 3, 2023, 1:09pm UTC](https://community.brain-map.org/t/projection-data-in-unionizes-having-is-injection-true/2326/1 "2023-05-03T13:09:05Z")

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Hi everyone,  
let me explain my question: what is the meaning of parameters like “projection\_volume” or “projection\_density” for unionizes entries having ‘is\_injection’ == True?  
I understand what these values represent regarding projection\_data, and I have read in the documentation that the funciont get\_projection\_matrix uses data for which ‘is\_injection’ is False, but I can’t understand why these entries are also available for data having ‘is\_injection’ == True.  
Thanks for the help

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**Author:** ![eitan.kaplan](https://avatars.discourse-cdn.com/v4/letter/e/5f8ce5/32.png) [@eitan.kaplan](https://community.brain-map.org/u/eitan.kaplan)\
**Post date:** [May 8, 2023, 3:29pm UTC](https://community.brain-map.org/t/projection-data-in-unionizes-having-is-injection-true/2326/2 "2023-05-08T15:29:22Z")

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Hi Pietro,  
Thanks for your interest. Can you please provide some additional context?  
E.g., what dataset(s) and documentation are you referring to in your question?

thanks

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**Author:** ![Pietro](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@Pietro](https://community.brain-map.org/u/Pietro)\
**Post date:** [May 8, 2023, 4:45pm UTC](https://community.brain-map.org/t/projection-data-in-unionizes-having-is-injection-true/2326/3 "2023-05-08T16:45:27Z")

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For sure, forgive me. I am referring to the allesdk python package, to manipulate Allen mouse brain data. In particular, I am using the mouse connectivity cache function to retrieve the unionizes structures.  
Hope that clarifies my question, thanks again.