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Vectorized some operations to make this faster #1

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Vectorized some operations to make this faster #1

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53 changes: 29 additions & 24 deletions rolling_ball.py
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Original file line number Diff line number Diff line change
Expand Up @@ -113,16 +113,19 @@ def roll_ball(ball, array):
either on or below the patch during this process is considered part of the
background.
"""
height, width = array.shape
height, width = array.shape
pixels = numpy.float32(array.flatten())
z_ball = ball.data
ball_width = ball.width
radius = ball_width / 2
cache = numpy.zeros(width * ball_width)

z_ball_arr = numpy.array(z_ball)

for y in range(-radius, height + radius):
next_line_to_write_in_cache = (y + radius) % ball_width
next_line_to_read = y + radius

if next_line_to_read < height:
src = next_line_to_read * width
dest = next_line_to_write_in_cache * width
Expand All @@ -138,6 +141,14 @@ def roll_ball(ball, array):
y_end = y + radius
if y_end >= height:
y_end = height - 1

k_yp = numpy.array(range(y_0, y_end + 1))
y_ball = y_ball_0
y_balls = numpy.array(range(y_ball, y_ball + (y_end + 1 - y_0)))

c_cache_pointers = (k_yp % ball_width) * width
c_bps = y_balls * ball_width

for x in range(-radius, width + radius):
z = float('inf')
x_0 = x - radius
Expand All @@ -147,33 +158,27 @@ def roll_ball(ball, array):
x_end = x + radius
if x_end >= width:
x_end = width - 1
y_ball = y_ball_0
for yp in range(y_0, y_end + 1):
cache_pointer = (yp % ball_width) * width + x_0
bp = x_ball_0 + y_ball * ball_width
for xp in range(x_0, x_end + 1):
z_reduced = cache[cache_pointer] - z_ball[bp]
if z > z_reduced:
z = z_reduced
cache_pointer += 1
bp += 1
y_ball += 1

y_ball = y_ball_0
for yp in range(y_0, y_end + 1):
p = x_0 + yp * width
bp = x_ball_0 + y_ball * ball_width
for xp in range(x_0, x_end + 1):
z_min = z + z_ball[bp]
if pixels[p] < z_min:
pixels[p] = z_min
p += 1
bp += 1
y_ball += 1

cache_pointers = c_cache_pointers + x_0
bps = x_ball_0 + c_bps

for c in range(0, x_end + 1 - x_0):
z_reduced = cache[cache_pointers + c] - z_ball_arr[bps + c]
m_val = numpy.min(z_reduced)
if m_val < z:
z = m_val

ps = x_0 + k_yp * width

for c in range(0, x_end + 1 - x_0):
z_mins = z + z_ball_arr[bps + c]
b_arr = pixels[ps+c] < z_mins
pixels[(ps+c)[b_arr]] = z_mins[b_arr]

return numpy.reshape(pixels, array.shape)



class RollingBall(object):
"""
A rolling ball (or actually a square part thereof).
Expand Down