[FIXED] How to effectively put data from X,Y,RGB_COLOR_INT pandas dataframe into image-like canvas numpy array?

Issue

I have pandas dataframe like this:

	x	y	color
0	826	1048	52416
1	583	1031	9745407
2	1873	558	6970623
3	1627	255	40618
4	49	1478	9745407
5	408	1863	14986239
6	111	1582	9745407
7	1334	1840	6970623
8	1908	1854	6970623

and numpy array which acts like a image canvas with shape (width, height, 4), pandas X and Y are within the width and height range of the canvas array.

What would be an effective way to split the RGBA integer values into it's respective channels and then put these into canvas as denoted by it's X,Y?

---

Currently I was able to separate the RGBA with numpy like this:

np_data = dataframe.to_numpy(np.uint32)
rgb_channels = np_data[:, 2].view(np.uint8).reshape(np_data[:, 2].shape[0], 4)

but I was unable to apply the values effectively thru numpy:

# This does not work
np.put(canvas, ((np_data[:, 0] * canvas.shape[0]) + (np_data[:, 1]), rgb_channels)
# I guess rgb_channels would have to have same size as canvas, as the index is applied to both (?) instead of the value argument being consumed for each index

The only way that works is this in python:

i = 0 # couldn't make enumerate or numpy.ndenumerate work properly
for x, y in np_data[:, [0, 1]]: # loop thru X,Y coordinates 
     canvas[x][y] = rgb_channels[i]

Solution

Your approach would go something like this:

np_data = (df['color'].to_numpy()
             .astype('uint32')        # uint32
             .view('uint8')           # convert to uint8
             .reshape(len(df), -1)    # reshape 
          )

# new image
canvas = np.zeros((10,10,4), dtype='uint8')

# slicing
canvas[df['x'], df['y']] = np_data

I would parse the channels explicitly like this

# use [3,2,1,0] if you are working with RGBA
powers = 256 ** np.array([2,1,0])

colors = (df.color.to_numpy()[:,None] & (powers*255))// powers

out = np.zeros((10,10,3), dtype='uint8')
out[df['x'], df['y']] = colors

Answered By - Quang Hoang

Answer Checked By - Willingham (PHPFixing Volunteer)