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add points in the surface profile with lables with arcpy and matplotlib

06-05-2018 12:55 AM
New Contributor


I have created surface profiles at various locations with the help of the python script from Xander Bakker.

The script works perfect. Now i want to add/show the reference points in each profile (see attachment) . How can i do it? any sggestions?

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4 Replies
MVP Emeritus

Is this Xander Bakker‌ 's code?

If so a link, or proper formatting would be nice


What were the results of the test?  

What have you tried?

New Contributor

Hi Dan,

Thanks for your response.

Yes its Xander Bakker's script

The link to the script is:

I am a beginner to python/arcpy. I tried but i think i am missing things like ,extract values to points and position it along the profileline and plot the z values on the profile with looping.

i have ammended the script at:

line 11, 53, 75, and 86

and i got this error

zp.append() # want to append raster values with loop
TypeError: append() takes exactly one argument (0 given)

ammended script is :

import arcpy
import os
import matplotlib.pyplot as plt
import numpy
import math

# settings for datasources
linesPath = "lines"
rasterPath = "raster"
pointPath =  "points" # point shapefile

# settings for output profiles PNG's
profileFolder = r"\test_arcpy\profile"
profilePrefix = "ArcPy_"
profilePostfix = "_new.png"
fldName = "hm"

# standard NoData mapping
NoDataValue = -9999

# describe raster
inDesc = arcpy.Describe(rasterPath)
rasMeanCellHeight = inDesc.MeanCellHeight
rasMeanCellWidth = inDesc.MeanCellWidth

# search cursor
fldShape = "SHAPE@"
flds = [fldShape, fldName]
with arcpy.da.SearchCursor(linesPath, flds) as curs:
    for row in curs:
        feat = row[0]
        profileName = row[1]

        # read extent of feature and create point for lower left corner
        extent = feat.extent
        print "Processing: {0}".format(profileName)
        pntLL = arcpy.Point(extent.XMin, extent.YMin)

        # determine number of rows and cols to extract from raster for this feature
        width = extent.width
        height = extent.height
        cols = int(width / rasMeanCellWidth)
        rows = int(height / rasMeanCellHeight)

        # create Numpy array for extent of feature
        arrNP = arcpy.RasterToNumPyArray(rasterPath, pntLL, cols, rows, NoDataValue)

        # create empty arrays for distance (d) and altitude (z) and NAP line (zv)
        d = []
        z = []
        zv = []
        zp = [] # voor point shape
        # loop through polyline and extract a point each meter
        for dist in range(0, int(feat.getLength("PLANAR"))):
            XYpointGeom = feat.positionAlongLine(dist, False)
            XYpoint = XYpointGeom.firstPoint

            # translate     XYpoint to     row, col (needs additional checking)
            c = int((XYpoint.X - pntLL.X) / rasMeanCellWidth)
            r2 = int((XYpoint.Y - pntLL.Y) / rasMeanCellHeight)
            r = rows - r2
            if c >= cols:
                c = cols-1
            if r >= rows:
                r = rows-1

            # extract value from raster and handle NoData
            zVal = arrNP[r,c]
            if not zVal == NoDataValue:
                zp.append() # want to append raster values with loop 

        # define output profile filename and figure size settings
        elevPNG = profileFolder + os.sep + profilePrefix + profileName + profilePostfix
        fig = plt.figure(figsize=(10, 3.5)) # inches

        # plot profile, define styles
        plt.plot(d,z,'ro',alpha=0.3, markersize=3)
        plt.plot(d,zp,'g',alpha=0.3, markersize=3)
        plt.xlabel('Distance from start')
        plt.title('Profile {0} using Python matplotlib'.format(profileName))

        # change font size
        plt.rcParams.update({'font.size': 8})

        # save graph as PNG
        fig.savefig(elevPNG, dpi=300)

# delete some objects
del arrNP, XYpointGeom, XYpoint
print "PNGs stored in: {0}".format(profileFolder)

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Esri Esteemed Contributor

Glad to hear the the script is working (at least for part of what you want to achieve). I assume that the zp list will need to be filled with data to be able to add it to the plot.  Since zp will have only a few values, you will need to determine when the values have to be added.

Are the reference values located exactly on the lines? What is the source for these points? To plot the points to location (xy) need to be translated to a distance from start.

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New Contributor

Hi Xander,

Thank you for your response.

Yes the script is working perfect.

Yes,  the reference values (points shapefile) located exactly on the lines.

The source for these points is the same raster (which used for lines )

You are right the "zp[ ] list need to be filled"

If you need more information dont hesitate ask.

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