# Understanding path mapper

**URL:** <https://discourse.mcneel.com/t/understanding-path-mapper/93660>\
**Category:** Grasshopper\
**Created:** [December 15, 2019, 5:38am UTC](https://discourse.mcneel.com/t/understanding-path-mapper/93660 "2019-12-15T05:38:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![archz2](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/archz2/32/488402_2.png) [@archz2](https://discourse.mcneel.com/u/archz2)\
**Post date:** [December 15, 2019, 5:38am UTC](https://discourse.mcneel.com/t/understanding-path-mapper/93660/1 "2019-12-15T05:38:17Z")

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I am learning to use path mapper.  
I understand so far only the usage of backslash once. If I use it again, it flattens the data I don’t understand why does that happen.

I am also not able to understand what does forward slash do?

[path mapper trying.gh](https://discourse.mcneel.com/uploads/short-url/imyC48HyyWmZLcx9v1R4ToM1JyV.gh) (11.1 KB)

 ![path mapper screenshot](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/b/1/b1240573dcf5298fb5eff4afd85c48e503a4e4af.jpeg)

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**Author:** ![Jakinta](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/jakinta/32/485854_2.png) [@Jakinta](https://discourse.mcneel.com/u/Jakinta)\
**Post date:** [December 15, 2019, 8:20am UTC](https://discourse.mcneel.com/t/understanding-path-mapper/93660/2 "2019-12-15T08:20:33Z")

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You can check these threads…

> [@Merge Data Tree Branches](https://discourse.mcneel.com/t/merge-data-tree-branches/67387/4):
>
> Hello medequ, There is an even simpler solution with path mapper : If you want to group paths 3 by 3, you just have to divide the path number by 3. Since path mapper rounds the value, {0}/3=0 becomes {0}, {1}/3=0.33 becomes {0} but {2}/3=0.66 becomes {1}. That is why I added 2 to the path number to make sure {0}, {1} and {2} would be in the same group. I hope this helps !

> [@Path Mapper Logic on Switching Placeholder Positions](https://discourse.mcneel.com/t/path-mapper-logic-on-switching-placeholder-positions/67309/5):
>
> Hi Kim Many thanks, your explanation is nice and clear and I got most of it. I am just a bit confused about the meaning of the notations. As you may see in the attached file, In Query 1: I could not figure out the difference between \ & / . In query 1, I have used (i\2) & (i/2) which I presume means partition into 2 parts & divide into 2 parts respectively. However, if you look at the ParaViewer, the N in the second tree differs from N=4 (i\2) to N=5 (i/2). In Query : When I use (i/25) I pr…

> [@Split in groups for area calculation](https://discourse.mcneel.com/t/split-in-groups-for-area-calculation/51257/4):
>
> / is regular division, \ is integer division. Integer division does not include any remainder.

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<div class="post-metadata">

**Author:** ![archz2](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/archz2/32/488402_2.png) [@archz2](https://discourse.mcneel.com/u/archz2)\
**Post date:** [December 15, 2019, 1:02pm UTC](https://discourse.mcneel.com/t/understanding-path-mapper/93660/3 "2019-12-15T13:02:32Z")

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> [@Jakinta](#):
>
> / is regular division, \ is integer division. Integer division does not include any remainder.

I am still not able to understand. If ‘/’ is regular division, then why I am getting five items in branch {2} ? And why does data get flattened by using '' twice in the first case?

'' partitions the list into branches having four items each. The last branch doesn’t have sufficient items, so it contains only three.