优化点-圆距离法 [英] Optimizing point - circle distance method
问题描述
我正在实现一种用于图像中圆圈检测的RANSAC算法.我分析了执行情况，然后得到了:
I'm implementing a RANSAC algorithm for circle detection in images. I profiled the execution and I get:
13699392 function calls in 799.981 seconds
Random listing order was used
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 0.000 0.000 {time.time}
579810 0.564 0.000 0.564 0.000 {getattr}
289905 2.343 0.000 8.661 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/linalg/blas.py:226(_get_funcs)
579810 0.124 0.000 0.124 0.000 {method 'get' of 'dict' objects}
289905 0.645 0.000 2.676 0.000 {map}
2954 0.005 0.000 0.005 0.000 {method 'transpose' of 'numpy.ndarray' objects}
2954 0.023 0.000 0.464 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/shape_base.py:179(vstack)
2954 2.373 0.001 2.373 0.001 {method 'read' of 'cv2.VideoCapture' objects}
579810 0.966 0.000 2.031 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/lib/function_base.py:550(asarray_chkfinite)
289905 10.164 0.000 24.316 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/linalg/basic.py:456(lstsq)
2954 1.090 0.000 1.090 0.000 {normalize}
1455433 3.827 0.000 3.827 0.000 {numpy.core.multiarray.array}
579810 2.899 0.000 3.148 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/numerictypes.py:949(_can_coerce_all)
1 0.000 0.000 0.000 0.000 {numpy.core.multiarray.empty}
2954 32.544 0.011 795.875 0.269 git/tra-python-processer/tra/ransac.py:31(image_search)
289905 0.714 0.000 38.644 0.000 git/tra-python-processer/tra/features.py:44(__init__)
289905 2.157 0.000 2.157 0.000 {method 'randint' of 'mtrand.RandomState' objects}
1 0.005 0.005 0.005 0.005 {VideoCapture}
289905 1.026 0.000 1.026 0.000 {method 'astype' of 'numpy.generic' objects}
2954 0.006 0.000 0.010 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/fromnumeric.py:495(transpose)
289905 11.303 0.000 37.930 0.000 git/tra-python-processer/tra/features.py:48(__gen)
3496584 0.343 0.000 0.343 0.000 {len}
2954 0.344 0.000 0.344 0.000 {numpy.core.multiarray.concatenate}
2954 3.214 0.001 3.214 0.001 {numpy.core.multiarray.where}
869715 0.575 0.000 0.575 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/fromnumeric.py:2514(size)
869715 0.778 0.000 2.278 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/numeric.py:394(asarray)
289905 716.946 0.002 716.946 0.002 git/tra-python-processer/tra/features.py:89(points_distance)
5908 0.015 0.000 0.031 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/numeric.py:464(asanyarray)
289905 0.275 0.000 0.275 0.000 {isinstance}
289905 0.342 0.000 9.003 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/linalg/lapack.py:255(get_lapack_funcs)
5908 0.058 0.000 0.097 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/shape_base.py:60(atleast_2d)
295813 0.089 0.000 0.089 0.000 {method 'append' of 'list' objects}
289905 0.645 0.000 3.793 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/numerictypes.py:970(find_common_type)
2954 0.221 0.000 0.221 0.000 {threshold}
1 0.000 0.000 0.000 0.000 {method 'get' of 'cv2.VideoCapture' objects}
1 0.000 0.000 0.000 0.000 git/tra-python-processer/tra/ransac.py:24(__init__)
2954 0.009 0.000 0.009 0.000 {numpy.core.multiarray.zeros}
579810 0.143 0.000 0.143 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/linalg/misc.py:126(_datacopied)
1 0.201 0.201 799.981 799.981 git/tra-python-processer/tra/ransac.py:122(video_processing)
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}
2954 1.528 0.001 1.528 0.001 {cvtColor}
289905 1.280 0.000 5.346 0.000 /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/linalg/blas.py:182(find_best_blas_type)
289905 0.198 0.000 0.198 0.000 {method 'index' of 'list' objects}
这是我第一次使用事件探查器，但是据我了解，最繁重的功能是features.py:89(points_distance)，这很容易实现:
It's first time I use profiler, however for what I can understand the function that is most heavy is features.py:89(points_distance) that comes out to be a very easy implementation:
def points_distance(self,points):
d = n.abs(\
n.sqrt(\
n.power(self.xc - points[:,0],2) + n.power(self.yc - points[:,1],2)
)\
- self.radius
)
return d
有什么建议吗?也许cython?
推荐答案
在points_distance中使用scipy.spatial.distance.cdist进行距离计算.
Use scipy.spatial.distance.cdist for the distance calculation in points_distance.
首先，使用纯Python和numpy优化代码.然后，如有必要，将关键部件移植到Cython.由于许多功能被重复调用了约100000次，因此对于这些部分，您应该从Cython那里获得一些加速.当然，除非计算瓶颈在距离计算中，否则它将限制整个执行时间.
First, optimize your code in pure Python and numpy. Then if necessary port the critical parts to Cython. Since a number of functions are called repeatedly a few ~100000 times, you should get some speed up from Cython for those parts. Unless, of course, the computational bottleneck is in the distance calculation, which will then limit the overall execution time.
顺便说一句，您应该按tottime对探查器结果进行排序，以便于阅读.
By the way, you should sort your profiler results by tottime so they are easier to read.
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