接下来是最简单的优化：
- 使用与
np.arange(...) 比较值而不是内部循环。
- 使用灰度图像而不是 3 通道 RGB。需要处理的数据减少 3 倍。
- 使用 np.uint8 类型而不是 np.float32，这样处理速度更快，并且不需要转换为 float32 即可进行 CV2 可视化。
以上所有这些优化都带来了巨大的加速（10x 次），我的运行时间是2.6 sec 而不是之前的27 sec。
另外一个我没有做的非常有用的优化是，在当前窗口中的整个数据的最大/最小值没有改变的情况下，您不需要重新计算以前的图像像素。只有在 max/min 改变的情况下，您才需要重新计算以前的图像数据。而且我预计您的真实数据会像外汇或比特币价格一样逐渐变化，因此窗口内的最大/最小变化非常不常见。
上面提到的优化1）-3）在下一个代码中实现：
import cv2
import numpy as np
import time
volumes = np.random.randint(low=0, high=200, size=10000)
print(volumes)
image_heigh = 128
image_width = 256
image_channel = 3
show_img = False
def nomralized(data, data_min, data_max, maximum_value):
nomamized_data = maximum_value * ((data - data_min) / (data_max - data_min))
return nomamized_data
start_time = time.time()
aranges = np.arange(image_heigh, dtype = np.int32)[:, None]
for ii in range(len(volumes)-image_width):
# ===================== part to optimize start
#final_image = np.zeros((image_heigh, image_width, image_channel), dtype = np.float32)
start = ii
end = ii + image_width
current_vols = volumes[start:end]
# nomalize data
vol_min = 0
vol_max = np.max(current_vols)
vol_norm = nomralized(data=current_vols,
data_min=vol_min,
data_max=vol_max,
maximum_value=image_heigh)
final_image = (aranges < vol_norm[None, :].astype(np.int32)).astype(np.uint8) * 255
# ===================== part to optimize end
if show_img:
cv2.imshow('ok', final_image)
cv2.waitKey(27)
print("total running time: ", (time.time() - start_time))
对于上面的代码，我只是对内部循环进行了一次优化，它甚至可以将2x 以上的代码加速到1.3 sec 的时间。但我也放回了 3 个通道加上 float32，这降低了速度导致最终的 2.8 sec, here is the code
如果不需要重新计算旧图像数据，则可以进行下一次优化。
要优化的主要内容是，您在每一步都重新计算几乎相同的整个图像，沿宽度移动 1 个像素。而不是这个，您需要计算整个图像一次，然后向右移动不是 1 个像素而是整个图像宽度。
那么经过这个优化运行时间就是0.08 sec。
并且只为显示动画进行 1 像素步进，而不是用于计算图像数据，如果您需要速度，应该只计算一次图像数据。
import cv2
import numpy as np
import time
volumes = np.random.randint(low=0, high=200, size=10000)
print(volumes)
image_heigh = 128
image_width = volumes.size #256
image_channel = 3
screen_width = 256
show_img = False
def nomralized(data, data_min, data_max, maximum_value):
nomamized_data = maximum_value * ((data - data_min) / (data_max - data_min))
return nomamized_data
start_time = time.time()
for ii in range(0, len(volumes), image_width):
# ===================== part to optimize start
final_image = np.zeros((image_heigh, image_width, image_channel))
start = ii
end = ii + image_width
current_vols = volumes[start:end]
# nomalize data
vol_min = 0
vol_max = np.max(current_vols)
vol_norm = nomralized(data=current_vols,
data_min=vol_min,
data_max=vol_max,
maximum_value=image_heigh)
for xxx in range(image_width):
final_image[:int(vol_norm[xxx]), xxx, :] = 1
# ===================== part to optimize end
if show_img:
for start in range(0, final_image.shape[1] - screen_width):
image = np.float32(final_image[:, start : start + screen_width])
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
cv2.imshow("ok", image)
cv2.waitKey(27)
print("total running time: ", (time.time() - start_time))
我还根据您的数据创建了动画图像：
如果您想创建相同的动画，只需将下一段代码附加到上述脚本的末尾：
# Needs: python -m pip install pillow
import PIL.Image
imgs = [PIL.Image.fromarray(final_image[:, start : start + screen_width].astype(np.uint8) * 255) for start in range(0, final_image.shape[1] - screen_width, 6)]
imgs[0].save('result.png', append_images = imgs[1:], save_all = True, lossless = True, duration = 100)
我还实现了实时流数据渲染/可视化的模拟。
-
live_stream() generator 在随机时间点吐出随机数量的数据，这是为了模拟数据的生成过程。
-
stream_fetcher() 监听实时流并将接收到的所有数据记录到 python 队列 @987654342@，这个 fetcher 在一个线程中运行。
-
renderer() 获取 fetcher 记录的数据，并通过您的数学公式和规范化过程将其渲染为图像，它渲染尽可能多的数据，导致图像具有不同的宽度，渲染的图像被保存到另一个队列 @987654344@。
-
visualizer() 通过获取尽可能多的可用渲染图像来可视化渲染数据。
所有函数都在单独的线程中运行，不会阻塞整个进程。此外，如果任何线程工作变慢，那么它会跳过一些数据以赶上当前的实时数据，因此每个队列都不会溢出。
另外你可能会看到可视化过程是跳跃的，这不是因为函数有些慢，而是因为直播在每个时间步中吐出不同数量的数据，这就是实时数据通常的表现。
在接下来的代码中，我还做了前面提到的额外优化，如果 min/max 没有改变，那就是不重新计算图像。
import cv2, numpy as np
import time, random, threading, queue
image_height = 256
image_width = 512
# Make results reproducible and deterministic
np.random.seed(0)
random.seed(0)
def live_stream():
last = 0.
while True:
a = np.random.uniform(low = -1., high = 1., size = random.randint(1, 20)).astype(np.float64).cumsum() + last
yield a
last = a[-1]
time.sleep(random.random() * 0.1)
q0 = queue.Queue()
def stream_fetcher():
for e in live_stream():
q0.put(e)
threading.Thread(target = stream_fetcher, daemon = True).start()
aranges = np.arange(image_height, dtype = np.int32)[:, None]
q1 = queue.Queue()
def renderer():
def normalized(data, data_min, data_max, maximum_value):
nomamized_data = maximum_value * ((data - data_min) / (data_max - data_min))
return nomamized_data
prev_image = np.zeros((image_height, 0), dtype = np.uint8)
prev_vols = np.zeros((0,), dtype = np.float64)
while True:
data = []
data.append(q0.get())
try:
while True:
data.append(q0.get(block = False))
except queue.Empty:
pass
vols = np.concatenate(data)[-image_width:]
prev_vols = prev_vols[-(image_width - vols.size) or prev_vols.size:]
concat_vols = np.concatenate((prev_vols, vols))[-image_width:]
vols_min, vols_max = np.amin(concat_vols), np.amax(concat_vols)
if prev_vols.size > 0 and (vols_min < np.amin(prev_vols) - 10 ** -8 or vols_max > np.amax(prev_vols) + 10 ** -8):
vols = concat_vols
prev_image = prev_image[:, :-prev_vols.size]
prev_vols = prev_vols[:0]
vols_norm = normalized(
data = vols, data_min = vols_min,
data_max = vols_max, maximum_value = image_height,
)
image = (aranges < vols_norm.astype(np.int32)[None, :]).astype(np.uint8) * 255
whole_image = np.concatenate((prev_image, image), axis = 1)[:, -image_width:]
q1.put(whole_image)
prev_image = whole_image
prev_vols = concat_vols
threading.Thread(target = renderer, daemon = True).start()
def visualizer():
imgs = []
while True:
data = []
data.append(q1.get())
try:
while True:
data.append(q1.get(block = False))
except queue.Empty:
pass
image = np.concatenate(data, axis = 1)[:, -image_width:]
cv2.imshow('ok', image)
cv2.waitKey(1)
if imgs is not None:
try:
# Needs: python -m pip install pillow
import PIL.Image
has_pil = True
except:
has_pil = False
imgs = None
if has_pil:
imgs.append(PIL.Image.fromarray(np.pad(image, ((0, 0), (image_width - image.shape[1], 0)), constant_values = 0)))
if len(imgs) >= 1000:
print('saving...', flush = True)
imgs[0].save('result.png', append_images = imgs[1:], save_all = True, lossless = True, duration = 100)
imgs = None
print('saved!', flush = True)
threading.Thread(target = visualizer, daemon = True).start()
while True:
time.sleep(0.1)
上面的实时过程模拟被渲染成result.png，我在下面显示：
我还决定通过使用更高级的matplotlib 而不是cv2 来改进可视化，以便能够显示轴并进行实时绘图。可视化图片如下：
接下来是一个基于matplotlib的代码，对应上面最后一张图片：
import cv2, numpy as np
import time, random, threading, queue
image_height = 256
image_width = 512
save_nsec = 20
dpi, fps = 100, 15
# Make results reproducible and deterministic
np.random.seed(0)
random.seed(0)
def live_stream():
last = 0.
pos = 0
while True:
a = np.random.uniform(low = -1., high = 1., size = random.randint(1, 30)).astype(np.float64).cumsum() + last
yield a, pos, pos + a.size - 1
pos += a.size
last = a[-1]
time.sleep(random.random() * 2.2 / fps)
q0 = queue.Queue()
def stream_fetcher():
for e in live_stream():
q0.put(e)
threading.Thread(target = stream_fetcher, daemon = True).start()
aranges = np.arange(image_height, dtype = np.int32)[:, None]
q1 = queue.Queue()
def renderer():
def normalized(data, data_min, data_max, maximum_value):
nomamized_data = maximum_value * ((data - data_min) / (data_max - data_min))
return nomamized_data
prev_image = np.zeros((image_height, 0), dtype = np.uint8)
prev_vols = np.zeros((0,), dtype = np.float64)
while True:
data = []
data.append(q0.get())
try:
while True:
data.append(q0.get(block = False))
except queue.Empty:
pass
data_vols = [e[0] for e in data]
data_minx, data_maxx = data[0][1], data[-1][2]
vols = np.concatenate(data_vols)[-image_width:]
prev_vols = prev_vols[-(image_width - vols.size) or prev_vols.size:]
concat_vols = np.concatenate((prev_vols, vols))[-image_width:]
vols_min, vols_max = np.amin(concat_vols), np.amax(concat_vols)
if prev_vols.size > 0 and (vols_min < np.amin(prev_vols) - 10 ** -8 or vols_max > np.amax(prev_vols) + 10 ** -8):
vols = concat_vols
prev_image = prev_image[:, :-prev_vols.size]
prev_vols = prev_vols[:0]
vols_norm = normalized(
data = vols, data_min = vols_min,
data_max = vols_max, maximum_value = image_height,
)
image = (aranges < vols_norm.astype(np.int32)[None, :]).astype(np.uint8) * 255
whole_image = np.concatenate((prev_image, image), axis = 1)[:, -image_width:]
q1.put((whole_image, data_maxx - whole_image.shape[1] + 1, data_maxx, vols_min, vols_max))
prev_image = whole_image
prev_vols = concat_vols
threading.Thread(target = renderer, daemon = True).start()
def visualizer():
import matplotlib.pyplot as plt, matplotlib.animation
def images():
while True:
data = []
data.append(q1.get())
try:
while True:
data.append(q1.get(block = False))
except queue.Empty:
pass
minx = min([e[1] for e in data])
maxx = min([e[2] for e in data])
miny = min([e[3] for e in data])
maxy = min([e[4] for e in data])
image = np.concatenate([e[0] for e in data], axis = 1)[:, -image_width:]
image = np.pad(image, ((0, 0), (image_width - image.shape[1], 0)), constant_values = 0)
image = np.repeat(image[:, :, None], 3, axis = -1)
yield image, minx, maxx, miny, maxy
it = images()
im = None
fig = plt.figure(figsize = (image_width / dpi, image_height / dpi), dpi = dpi)
def animate_func(i):
nonlocal it, im, fig
image, minx, maxx, miny, maxy = next(it)
print(f'.', end = '', flush = True)
if im is None:
im = plt.imshow(image, interpolation = 'none', aspect = 'auto')
else:
im.set_array(image)
im.set_extent((minx, maxx, miny, maxy))
return [im]
anim = matplotlib.animation.FuncAnimation(fig, animate_func, frames = round(save_nsec * fps), interval = 1000 / fps)
print('saving...', end = '', flush = True)
#anim.save('result.mp4', fps = fps, dpi = dpi, extra_args = ['-vcodec', 'libx264'])
anim.save('result.gif', fps = fps, dpi = dpi, writer = 'imagemagick')
print('saved!', end = '', flush = True)
plt.show()
threading.Thread(target = visualizer, daemon = True).start()
while True:
time.sleep(0.1)
然后我决定用 RGB 调色板为最后一张图像上色，峰值越高越偏红，如果它在中间越偏绿，如果是足够低，那么它就更蓝了。下面的结果图片是由this coloring code实现的：
下面还有一个彩色动画，线条样式而不是条形样式，在this code的帮助下：