Polyline NumPy Array to Pandas DataFrame: StElevation and EndElevation?

PeterWilson

I have converted a feature class (polylines) to a numpy array and have expoded the polylines to vertices using the "explode_to_points" method. I would like to convert the output numpy array to a pandas dataframe that will replicate the line segments that make up the polyline so that I land up with the following columns:

The table above was achieved by using "Split Line At Vertices". The fields "STElev" and "EndElev" are the Start Elevation and End Elevation of the line segments determined using "Calculate Geometry". The field "STElevation" and "EndElevation" is the change in elevation determined by subtracting the elevation from the first "STElev" which in this case is 355.8495.

The output numpy array from converting my feature class (polylines) and exploding the features to vertices is:

The values are:

[(DrainID, X, Y, Z)....] for each vertice

<SPAN class="string token">'''
Created on 01 Jul 2017

@author: PeterW
'''</SPAN>
<SPAN class="comment token"># import modules and site-packages</SPAN>
<SPAN class="keyword token">import</SPAN> numpy <SPAN class="keyword token">as</SPAN> np
<SPAN class="keyword token">import</SPAN> pandas <SPAN class="keyword token">as</SPAN> pd
<SPAN class="keyword token">from</SPAN> pathlib <SPAN class="keyword token">import</SPAN> Path
<SPAN class="keyword token">import</SPAN> arcpy

<SPAN class="comment token"># set environment settings</SPAN>
arcpy<SPAN class="punctuation token">.</SPAN>env<SPAN class="punctuation token">.</SPAN>overwriteOutput <SPAN class="operator token">=</SPAN> <SPAN class="token boolean">True</SPAN>

<SPAN class="comment token"># check out extensions</SPAN>
arcpy<SPAN class="punctuation token">.</SPAN>CheckOutExtension<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"3D"</SPAN><SPAN class="punctuation token">)</SPAN>

<SPAN class="keyword token">def</SPAN> <SPAN class="token function">longestflowpath_3d</SPAN><SPAN class="punctuation token">(</SPAN>dtm<SPAN class="punctuation token">,</SPAN> lfp_2d<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="string token">"""Generate LongestFlowPath 3D
&nbsp;&nbsp;&nbsp; from LongestFlowPath 2D and DTM"""</SPAN>
&nbsp;&nbsp;&nbsp; output_gdb <SPAN class="operator token">=</SPAN> str<SPAN class="punctuation token">(</SPAN>Path<SPAN class="punctuation token">(</SPAN>lfp_2d<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>parents<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; lfp_3d <SPAN class="operator token">=</SPAN> <SPAN class="string token">"{0}\\{1}"</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>output_gdb<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"lfp_3d"</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; lfp_3d <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>InterpolateShape_3d<SPAN class="punctuation token">(</SPAN>dtm<SPAN class="punctuation token">,</SPAN> lfp_2d<SPAN class="punctuation token">,</SPAN> lfp_3d<SPAN class="punctuation token">,</SPAN> vertices_only<SPAN class="operator token">=</SPAN><SPAN class="token boolean">True</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; arcpy<SPAN class="punctuation token">.</SPAN>FlipLine_edit<SPAN class="punctuation token">(</SPAN>lfp_3d<SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> lfp_3d


<SPAN class="keyword token">def</SPAN> <SPAN class="token function">area_under_profile</SPAN><SPAN class="punctuation token">(</SPAN>lfp_3d<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="string token">"""Determine the Equal Area Slope
&nbsp;&nbsp;&nbsp; for each Drainage Area's Longest
&nbsp;&nbsp;&nbsp; Flowpath"""</SPAN>
&nbsp;&nbsp;&nbsp; arr <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>da<SPAN class="punctuation token">.</SPAN>FeatureClassToNumPyArray<SPAN class="punctuation token">(</SPAN>lfp_3d<SPAN class="punctuation token">,</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="string token">"DrainID"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"SHAPE@X"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"SHAPE@Y"</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">"SHAPE@Z"</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN> explode_to_points<SPAN class="operator token">=</SPAN><SPAN class="token boolean">True</SPAN><SPAN class="punctuation token">)</SPAN>&nbsp; <SPAN class="comment token"># @UndefinedVariable</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN><SPAN class="punctuation token">(</SPAN>arr<SPAN class="punctuation token">)</SPAN>


<SPAN class="keyword token">def</SPAN> <SPAN class="token function">equal_area_slope</SPAN><SPAN class="punctuation token">(</SPAN>dtm<SPAN class="punctuation token">,</SPAN> lfp_2d<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="string token">"""Determine the Equal Area Slope
&nbsp;&nbsp;&nbsp; for each Drainage Area's Longest
&nbsp;&nbsp;&nbsp; Flowpath"""</SPAN>
&nbsp;&nbsp;&nbsp; lfp_3d <SPAN class="operator token">=</SPAN> longestflowpath_3d<SPAN class="punctuation token">(</SPAN>dtm<SPAN class="punctuation token">,</SPAN> lfp_2d<SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; area_under_profile<SPAN class="punctuation token">(</SPAN>lfp_3d<SPAN class="punctuation token">)</SPAN>


<SPAN class="keyword token">if</SPAN> __name__ <SPAN class="operator token">==</SPAN> <SPAN class="string token">"__main__"</SPAN><SPAN class="punctuation token">:</SPAN>
&nbsp;&nbsp;&nbsp; dtm <SPAN class="operator token">=</SPAN> r<SPAN class="string token">"E:\Projects\2016\G113665\geoHydro\DTM2\raw1"</SPAN>
&nbsp;&nbsp;&nbsp; lfp_2d <SPAN class="operator token">=</SPAN> r<SPAN class="string token">"E:\Projects\2016\G113665\geoHydro\Model02\Results.gdb\LongestFlowPath_2D_Orig"</SPAN>
&nbsp;&nbsp;&nbsp; equal_area_slope<SPAN class="punctuation token">(</SPAN>dtm<SPAN class="punctuation token">,</SPAN> lfp_2d<SPAN class="punctuation token">)</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

My current Python Module

How can I convert the current numpy array to a pandas dataframe that will restructure the vertices (DrainID, X, Y, Z) to (DrainID, STElevation (change in elevation), EndElevation (change in elevation), DistM (Length of segment)?

polyline_split.zip

polyline_unsplit.zip

DanPatterson_Retired

Peter, there is a caveat in that function which states ... this can be simplified to 4 lines for 2D .... 

That is the full code when needing to determine lengths/distances in higher dimensions....

You need not worry about it unless you are working with 3D data (conventional X,Y,Z) or 4D data(3D shifted by a distance over time)

Plus the 'cal' function uses einsum which is a bit of an overkill to determine distance between points, for instance, that can be written much shorter if one is using polygons that one is normally going to encounter.  The methods that you will find on the forum will crawl when you are working with objects with millions of vertices (beyond the scope of ArcMap in any event).  I just like to use what works for the cases that I use.

Pythagorean theorem is good enough to determine 2D length if that is all you need.