Sum each branch of a datatree using python

This should be a relatively simple question but I cant seem to work it out

I have a datatree which has two branches, each branch contains multiple floats,

using python how could I sum each data tree branch and update the datatree so that it contains only the sum of each branch,

Thank you!

Replies to This Discussion

Permalink Reply by Anders Holden Deleuran on May 4, 2015 at 8:39am

If you set your input parameter to "List Access" instead of "Tree Access" you can just let GH do the rest (see attached). Otherwise you will have to operate on DataTrees which is also an option, but quite a bit more involved.

Attachments:

150504_PySumList.gh, 5 KB

Permalink Reply by djordje on May 4, 2015 at 8:59am

Here are the data trees options (clearing branches then inserting sums, or creating a new data tree and appending sums to its branches).

Attachments:

dataTreeSumBranches.gh, 12 KB

Permalink Reply by Anders Holden Deleuran on May 4, 2015 at 9:13am

Heh, I just did the same. Seemed appropriate :)

Attachments:

150504_PySumList_DataTreeAccess.gh, 7 KB

Permalink Reply by djordje on May 4, 2015 at 12:38pm

Nice!

Permalink Reply by Anton Szilasi on May 4, 2015 at 5:14pm

Hi Djordje

Thanks Im actually doing it in a component - (Creating a datatree in the component then summing each branch in the component)

Thank you Anders and Dominik too!

Permalink Reply by djordje on May 4, 2015 at 5:25pm

Hi Anton,

Nothing changes. You can still clear the branches of that created data tree and insert its sums instead (if you do not need that previous data tree). Or if you need both of them (initial and sum one), create a new data tree and then add the sums to its branches.

Permalink Reply by Anton Szilasi on August 21, 2015 at 6:24am

Hi Andres

Can I ask you a question, in the code that you've written here:

import Grasshopper as gh

a = gh.DataTree[float]()
for i in range(x.BranchCount):
a.Add(sum(x.Branch(i)),x.Paths.Item[i])

the line - gh.DataTree[float]() within the [] is declaring the type of the objects that the datatree takes right?

As the Grasshopper SDK DataTree constructor needs a type - DataTree(T) Constructor.

Why do we use [] to denote the type? shouldn't we use () like in the Grasshopper SDK also are these types python types? I tried using string in the type but it didnt work.

I'm a bit confused about this

Thank you!

Anton

Permalink Reply by djordje on August 21, 2015 at 1:10pm

Hi Anton,

The question is not directed to me, I've seen it today, and just in case Anders is preparing for tomorrow's workshop:

That's how you define types in ironpython (which is what grasshopper and Rhino are using). If I remember correctly you code both in C# and python. The C#'s <someType> syntax in ironpython is: [someType].
Example of usage is DataTree in this case, or System.Collections in case you need them (few RhinoCommon methods for some strange reason do not not accept standard builtin data types: