# \[?\] Create Multi-coloured tree plot?

**URL:** <https://community.wolfram.com/t/create-multi-coloured-tree-plot/11265>\
**Category:** Questions\
**Tags:** graphics-and-visualization, graphs-and-networks, computational-notebooks\
**Created:** [September 17, 2017, 4:22am UTC](https://community.wolfram.com/t/create-multi-coloured-tree-plot/11265 "2017-09-17T04:22:34Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![dyfroedd](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@dyfroedd](https://community.wolfram.com/u/dyfroedd)\
**Post date:** [September 17, 2017, 4:22am UTC](https://community.wolfram.com/t/create-multi-coloured-tree-plot/11265/1 "2017-09-17T04:22:34Z")

</div>

I am trying to create a multi-coloured tree plot (Mathematica 9) where each branch is coloured according to its parent node value. For example, for a tree plot with three nodes, n1, n2 and n3, coming from a single parent node (n0), the children nodes of n1 should be red & n2 green and n3 should be blue.

```
TreePlot[nodes, EdgeRenderingFunction -> ({Red, Line[#1]} &), VertexRenderingFunction -> (Inset[Row[{If[Last[#2] > 3, Rotate[Last[#2], 90 Degree], Last[#2]]}], #1, Background -> White] &)]

```

I am using the EdgeRenderingFunction for this within the following expression which will render the edges of the tree plot. The problem, I think, is that the If statement is not evaluated straight away and so the compiler does not recognise the first option (contained within the If statement) as a relevant one. As you can see I’m trying to create a tree plot with red and green branches.

```
TreePlot[nodes, EdgeRenderingFunction -> ({If[Last[#2] === 1, Red, Green], Line[#1]} &), VertexRenderingFunction -> (Inset[Row[{If[Last[#2] > 3, Rotate[Last[#2], 90 Degree], Last[#2]]}], #1, Background -> White] &)]

```

Here, all edges were rendered the same colour. Not sure whether `EdgeRenderingFunction[]` renders the whole tree object instead of it’s parts or whether I need to include the edge colour into the tree data structure (node table)?

Here’s a sample of the node list:  
{{0} → {0, 1}, {0} → {0, 2}, {0} → {0, 3}, {0, 1} → {0, 1, 4}, {0, 1} → {0, 1, 5}, {0, 1} → {0, 1, 6}, {0, 1} → {0, 1, 7}, {0, 1} → {0, 1, 8}…

Thanks for your time in helping me with this.

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<div class="post-metadata">

**Author:** ![neils](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/neils/32/20595_2.png) [@neils](https://community.wolfram.com/u/neils)\
**Post date:** [September 17, 2017, 4:45pm UTC](https://community.wolfram.com/t/create-multi-coloured-tree-plot/11265/2 "2017-09-17T16:45:29Z")

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Marc,

The If comparison needs to be a node, not a number:

```
nodes = {{0} -> {0, 1}, {0} -> {0, 2}, {0} -> {0, 3}, {0, 1} -> {0, 1,
     4}, {0, 1} -> {0, 1, 5}, {0, 1} -> {0, 1, 6}, {0, 1} -> {0, 1, 
    7}, {0, 1} -> {0, 1, 8}, {0, 1} -> {0, 1}}
TreePlot[nodes, 
 EdgeRenderingFunction -> ({If[First[#2] == {0, 1}, Red, Green], 
     Arrow[#1]} &), 
 VertexRenderingFunction -> (Inset[
     Row[{If[Last[#2] > 3, Rotate[Last[#2], 90 Degree], 
        Last[#2]]}], #1, Background -> White] &)]

```

to get

 ![ScreenShot2017-09-17at12.30.38PM.png](https://global.discourse-cdn.com/wolfram/original/3X/9/0/90b6a6047adcd7e7cd149f6967519c4ed4e61db0.png)

or a single node:

```
TreePlot[nodes,EdgeRenderingFunction->({If[First[#2]=={0},Red,Green],Arrow[#1]}&),VertexRenderingFunction->(Inset[Row[{If[Last[#2]>3,Rotate[Last[#2],90 Degree],Last[#2]]}],#1,Background->White]&)]

```

to get

 ![ScreenShot2017-09-17at12.38.37PM.png](https://global.discourse-cdn.com/wolfram/original/2X/7/710afb9241c51f137f0adac110ecbf2c6c385044.png)

I am not sure why testing if Last[#2] equals a number throws an error since Mathematica knows that a list can’t equal a number but either way, you need a list in that position, not a number. I guess by throwing an error it lets you know that it can never do that test properly.