Plot raster/array#

Library#

  • import the libraries

1from Hapi.visualizer import Visualize as vis
2import gdal
3import pandas as pd

Paths#

  • define paths to the raster file.

1RasterAPath = "data/GIS/Hapi_GIS_Data/acc4000.tif"

Read the raster#

-To plot the array you need to read the raster using gdal.

1src = gdal.Open(RasterAPath)

Default Plot#

  • Then using all the default parameters in the PlotArray method you can directly plot the gdal.Dataset.

1vis.PlotArray(src)
2
3(<Figure size 576x576 with 2 Axes>,
4 <AxesSubplot:title={'center':'Total Discharge'}>)
_images/default-plot.png
  • However as you see in the plot you might need to adjust the color to different color scheme or the

    display of the colorbar, colored label. you might don’t need to display the labels showing the values of each cell, and for all of these decisions there are a lot of customizable parameters.

Basic Figure features#

  • First for the size of the figure you have to pass a tuple with the width and height.

  • Figsize[tuple], optional

    figure size. The default is (8,8).

  • Title[str], optional

    title of the plot. The default is ‘Total Discharge’.

  • titlesize[integer], optional

    title size. The default is 15.

1Figsize=(8, 8)
2Title='Flow Accumulation map'
3titlesize=15
4
5vis.PlotArray(src, Figsize=Figsize, Title=Title, titlesize=titlesize)
6
7
8(<Figure size 576x576 with 2 Axes>,
9<AxesSubplot:title={'center':'Flow Accumulation map'}>)
_images/basic_feature.png

Color Bar#

  • Cbarlength[float], optional

    ratio to control the height of the colorbar. The default is 0.75.

  • orientation[string], optional

    orintation of the colorbar horizontal/vertical. The default is ‘vertical’.

  • cbarlabelsizeinteger, optional

    size of the color bar label. The default is 12.

  • cbarlabelstr, optional

    label of the color bar. The default is ‘Discharge m3/s’.

  • rotation[number], optional

    rotation of the colorbar label. The default is -90.

  • TicksSpacing[integer], optional

    Spacing in the colorbar ticks. The default is 2.

 1Cbarlength=0.75
 2orientation='vertical'
 3cbarlabelsize=12
 4cbarlabel= 'cbar label'
 5rotation=-20
 6TicksSpacing=10
 7
 8vis.PlotArray(src, Cbarlength=Cbarlength, orientation=orientation,
 9              cbarlabelsize=cbarlabelsize, cbarlabel=cbarlabel, rotation=rotation,
10              TicksSpacing=TicksSpacing)
11
12
13(<Figure size 576x576 with 2 Axes>,
14<AxesSubplot:title={'center':'Total Discharge'}>)
_images/color_bar.png

Color Schame#

  • ColorScaleinteger, optional

    there are 5 options to change the scale of the colors. The default is 1. 1- ColorScale 1 is the normal scale 2- ColorScale 2 is the power scale 3- ColorScale 3 is the SymLogNorm scale 4- ColorScale 4 is the PowerNorm scale 5- ColorScale 5 is the BoundaryNorm scale

  • gamma[float], optional

    value needed for option 2 . The default is 1./2..

  • linthresh[float], optional

    value needed for option 3. The default is 0.0001.

  • linscale[float], optional

    value needed for option 3. The default is 0.001.

  • midpoint[float], optional

    value needed for option 5. The default is 0.

  • cmap[str], optional

    color style. The default is ‘coolwarm_r’.

1# for normal linear scale
2ColorScale = 1
3cmap='terrain'
4vis.PlotArray(src, ColorScale=ColorScale, cmap=cmap, TicksSpacing=TicksSpacing)
5
6(<Figure size 576x576 with 2 Axes>,
7<AxesSubplot:title={'center':'Total Discharge'}>)
_images/color_scheme.png

Power Scale#

  • The more you lower the value of gamma the more of the color bar you give to the lower value range

 1ColorScale = 2
 2gamma=0.5
 3
 4vis.PlotArray(src, ColorScale=ColorScale, cmap=cmap, gamma=gamma,
 5              TicksSpacing=TicksSpacing)
 6
 7vis.PlotArray(src, ColorScale=ColorScale, cmap=cmap, gamma=0.4,
 8          TicksSpacing=TicksSpacing)
 9
10vis.PlotArray(src, ColorScale=ColorScale, cmap=cmap, gamma=0.2,
11          TicksSpacing=TicksSpacing)
12
13(<Figure size 576x576 with 2 Axes>,
14<AxesSubplot:title={'center':'Total Discharge'}>)
_images/power_scale5.png _images/power_scale4.png _images/power_scale2.png

SymLogNorm scale#

1ColorScale = 3
2linscale=0.001
3linthresh=0.0001
4vis.PlotArray(src, ColorScale=ColorScale, linscale=linscale, linthresh=linthresh,
5              cmap=cmap, TicksSpacing=TicksSpacing)
6
7
8(<Figure size 576x576 with 2 Axes>,
9<AxesSubplot:title={'center':'Total Discharge'}>)
_images/symlognorm.png

PowerNorm scale#

1ColorScale = 4
2vis.PlotArray(src, ColorScale=ColorScale,
3          cmap=cmap, TicksSpacing=TicksSpacing)
4
5(<Figure size 576x576 with 2 Axes>,
6<AxesSubplot:title={'center':'Total Discharge'}>)
_images/powernorm.png

Color scale 5#

1ColorScale = 5
2midpoint=20
3vis.PlotArray(src, ColorScale=ColorScale, midpoint=midpoint,
4              cmap=cmap, TicksSpacing=TicksSpacing)
5
6
7(<Figure size 576x576 with 2 Axes>,
8<AxesSubplot:title={'center':'Total Discharge'}>)
_images/midpoint.png

Cell value label#

  • display_cellvalue[bool]

    True if you want to display the values of the cells as a text

  • NumSizeinteger, optional

    size of the numbers plotted intop of each cells. The default is 8.

  • Backgroundcolorthreshold[float/integer], optional

    threshold value if the value of the cell is greater, the plotted numbers will be black and if smaller the plotted number will be white if None given the maxvalue/2 will be considered. The default is None.

 1display_cellvalue = True
 2NumSize=8
 3Backgroundcolorthreshold=None
 4
 5vis.PlotArray(src, display_cellvalue=display_cellvalue, NumSize=NumSize,
 6              Backgroundcolorthreshold=Backgroundcolorthreshold,
 7              TicksSpacing=TicksSpacing)
 8
 9(<Figure size 576x576 with 2 Axes>,
10<AxesSubplot:title={'center':'Total Discharge'}>)
_images/cellvalue.png

Plot Points#

if you have points that you want to display in the map you can read it into a dataframe in condition that it has two columns “x”, “y” which are the coordinates of the points of theand they have to be in the same coordinate system as the raster.

  • read the points

1pointsPath = "data/GIS/Hapi_GIS_Data/points.csv"
2points = pd.read_csv(pointsPath)

  • plot the points

 1Gaugecolor='blue'
 2Gaugesize=100
 3IDcolor="green"
 4IDsize=20
 5vis.PlotArray(src, Gaugecolor=Gaugecolor, Gaugesize=Gaugesize,
 6              IDcolor=IDcolor, IDsize=IDsize, points=points,
 7              display_cellvalue=display_cellvalue, NumSize=NumSize,
 8              Backgroundcolorthreshold=Backgroundcolorthreshold,
 9              TicksSpacing=TicksSpacing)
10
11(<Figure size 576x576 with 2 Axes>,
12<AxesSubplot:title={'center':'Total Discharge'}>)
_images/plotpoints.png