Jupyter Snippet CB2nd 01_blocks

3.1. Teaching programming in the Notebook with IPython blocks

import time
from IPython.display import clear_output
from ipythonblocks import BlockGrid, colors

grid = BlockGrid(width=5, height=5,
                 fill=colors['Purple'])
grid.show()

grid[0, 0] = colors['Lime']
grid[-1, 0] = colors['Lime']
grid[:, -1] = colors['Lime']
grid.show()

n = 5
grid = BlockGrid(width=2 * n + 1,
                 height=2 * n + 1,
                 fill=colors['White'])
A = grid[n + 1:, :n]
B = grid[:n, n + 1:]
C = grid[n + 1:, n + 1:]
A[:, :] = colors['Cyan']
B[:, :] = colors['Lime']
C[:, :] = colors['Yellow']
grid.show()

for i in range(n):
    for j in range(n):
        # We reset the matrix colors.
        A[:, :] = colors['Cyan']
        B[:, :] = colors['Lime']
        C[:, :] = colors['Yellow']
        # We highlight the adequate rows
        # and columns in red.
        A[i, :] = colors['Red']
        B[:, j] = colors['Red']
        C[i, j] = colors['Red']
        # We animate the grid in the loop.
        clear_output()
        grid.show()
        time.sleep(.25)

# We downsample the image by a factor of 4 for
# performance reasons.
img = plt.imread('https://github.com/ipython-books/'
                 'cookbook-2nd-data/blob/master/'
                 'beach.png?raw=true')[::4, ::4, :]

rgb = [img[..., i].ravel() for i in range(3)]

height, width = img.shape[:2]
grid = BlockGrid(width=width, height=height,
                 block_size=2, lines_on=False)
for block, r, g, b in zip(grid, *rgb):
    block.rgb = (r * 255, g * 255, b * 255)
grid.show()