Loading images into memory map

It is recommended to load large files into memory maps. Memory-mapped files only load a small part of large files. NumPy memory maps are array-like. In this example, we will generate an image of colored squares and load it into a memory map.

Getting ready

If necessary, install Matplotlib. The See Also section of this recipe has a reference to the corresponding recipe.

How to do it...

We will begin by initializing arrays.

1. First, we need to initialize the following arrays:

   • an array that holds the image data

   • an array with random coordinates of the centers of the squares

   • an array with random radii of the squares

   • an array with random colors of the squares

     img = numpy.zeros((N, N), numpy.uint8)
     centers = numpy.random.random_integers(0, N, size=(NSQUARES, 2))
     radii = numpy.random.randint(0, N/9, size=NSQUARES)
     colors = numpy.random.randint(100, 255, size=NSQUARES)

   Initialize the arrays as follows:

   As you can see, we are initializing the first array to zeroes. The other arrays...