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https://github.com/rrwen/qgis-rasterarray

Raster data example in QGIS using numpy arrays
https://github.com/rrwen/qgis-rasterarray

cell console conway data gameoflife gdal geographic geolocation gis numpy qgis raster

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Raster data example in QGIS using numpy arrays

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# Quantum GIS Raster Array Module 



A Python module for manipulating geographic raster image data in QGIS using numpy arrays. Includes a demonstration for Conway's Game of Life.  



* **View the [Game of Life Blog Post](https://gis.blog.torontomu.ca/2015/03/08/a-raster-based-game-of-life-using-python-in-qgis/)**

* **View [Example.txt](Example.txt) for an example run.** 

 

_Dependencies: QGIS 2.6.1 Brighton, Python 2.7_ 

 

 

#  QGIS Python Console Setup

  

  

 1. Go to the python command console in QGIS  

   `(Plugins > Python Console)`

  

 2. Enter in the console:  

    `import sys`

  

 3. Find the location path of this script  

    `C:\\User\\Desktop`

  

 4. Append it to the QGIS system paths with:  

       `sys.path.append(FILE_PATH_HERE)`   

       `sys.path.append ("C:\\User\\Desktop")`

      

 5.  Import the Cells class for use in the console:  

    `from RasterArray import *`

  

  

# Cells

  

  

##  A. Creating the Cells Object  

  

 * Create a Cells object as a random array:

   

    `cellsObject = Cells()`

  

 * Create a Cells object as a filled array:

   

    `cellsObject = Cells(inRaster=n)`  

    + n is the value to fill the array with

  

 * Create a Cells object as a custom array:

   

    `cellsObject = Cells(inRaster=[(r1c1,r1c2,r1c3),(r2c1,r2c2,r2c3)])`  

    + r1c1..rncn refers to row 1 (r1) and column 1(c1) to row n (rn) and column n (cn)  

    + The containers [] define a list and () define a tuple

  

 * Create a Cells object with a raster file:

 

    `cellsObject = Cells ("path_to_raster_file")`  

    + "path_to_raster_file" is the location of the raster with

      extension

  

##  B. Modifying and Obtaining Cell Values  

   

 * Modify a cell value:

   

    `cellsObject.modify(x, y, value)`  

    + x and y are the coordinates of the cell to modify  

    + value is the value to replace the cell value at the location  

    + for non-geographic coordinates, use (x, y, value, geographic=False)

  

 * Obtain a cell value:

 

    `cellsObject.get(x, y)`  

    + x and y are coordinates of the cell to obtain  

    + for non-geographic coordinates, use (x, y, value, geographic=False)

  

##  C. Output to Raster TIF  

  

 * Output a raster representing the changes:

 

    `cellsObject.toRaster("path_to_output_raster_file")`  

    + "path_to_output_raster_file" is the location of the output

      raster file with extension

  

##  D. Additional Settings  

  

 * Set the band of the raster

   

    `cellsObject = Cells (nband=n)`  

    + n is band number of the input raster, does not work for default

  

 * Set the spatial reference system of the randomly generated raster

   

    `cellsObject = Cells (EPSG=coorSys)`  

    + coorSys is the EPSG number of the spatial reference of the randomly generated raster

  

 * Setting the dimensions and cell measurements of the randomly generated raster

   

    `cellsObject = Cells (cols=c,rows=r,pixelWidth=w,pixelHeight)`  

    + c and r are inputs in whole numbers to specify the number of columns and rows  

    + w and h are inputs in real numbers to specify the width and height of cells

  

  

# GameofLife

  

  

##  A. Creating a GameofLife Object  

  

 * Create a GameofLife object:  



    `GoLObject = GameofLife()`

  

##  B. Cycling the Game Board  

  

 * Cycle the game n times:  



    `GoLObject.cycle(n)`  

    + n is the number of times to cycle the gaming board

  

 * Reset the game:



    `x.reset()`  

    + reset the gaming board to the initial state

  

##  C. Additional Settings  

  

### C1. Data  

  

 * Set the initial board when creating the GameofLife object:

   

    `GoLObject = GameofLife(raster="path_to_raster_file")`  

    + "path_to_raster_file" is the path to the raster file with extension to be used for the initial board

  

 * Set whether or not to overwrite cycles:



    `GoLObject.overwrite = boolean`  

    + boolean is set to True or False, where True overwrites each cycle, and False does not overwrite each cycle

  

 * Set the spatial reference system of the randomly generated raster

   

    `GoLObject = GameofLife(EPSG=coorSys)`  

    + coorSys is the EPSG number of the spatial reference of the randomly generated raster

  

### C2. Aesthetics  

  

 * Set the style of the start and cycle boards with a qml file:



    `GoLObject.qmlStyle = "path_to_qml_file"`  

    + "path_to_qml_file" is the path to the QGIS .qml style file used for changing the style of the output board

  

 * Set the refresh speed:



    `GoLObject.speed = x`  

    + x is the refresh speed in seconds before processing the next cycle

  

### C3. Dimensions  

  

 * Set the width and height when creating the GameofLife object:

   

    `GoLObject = GameofLife(width=w, height=h)`  

    + w and h are inputs in whole numbers to specify the width and height of the randomly generated board

  

* Set the raster cell sizes when creating the GameofLife object:



    `GoLObject = GameofLife(cellWidth=w, cellHeight=h)`  

    + w and h are inputs in real numbers to specify the width and height of cells in the randomly generated board

  

  

#  Authors

  

  

* Richard Wen ([email protected])

* Dr. Claus Rinner ([email protected])