在python中从图像创建大的邻接矩阵 [英] Creating large adjacency matrix from image in python
问题描述
我想在python中从图像中创建一个大的,加权的邻接矩阵(所以很多顶点...按照10 ^ 5个顶点的顺序)。相邻像素之间的权重是颜色渐变(我注意到这一点)。通过遍历像素来做它非常缓慢......需要4分钟以上。 :-(有什么库可以在合理的时间内做到这一点吗?
以下是我的代码,运行速度很慢:
def indToCoord(ind,w,h):
x = ind%w
y =(ind - x)/ h
return (x,y)
def isAdj(p1,p2,im):
adj = []
w,h = im.size
x1,y1 = p1
x2,y2 = p2
if(x1,y1)==(x2,y2):
return 0
elif abs(x1 - x2)> 1:
返回0
elif abs(y1 - y2)> 1:
return 0
elif abs(x1 - x2)+ abs(y1 - y2)> = 2:
返回0
返回util.colorGradient(im,p1,p2)
def adjForPixel(pixels,p1,im):
return [isAdj(p1 ,p2,im)for p2 in pixels]
#以下是我用来从图像创建邻接矩阵的函数
def getAdjMatrix(im):
width, height = im.size
pixels = [x(x,y)for x in xrange(width)for y in xrange(height)]
pixelAdjMatr = [adjForPixel(pixels,p,im)for p in pixels]
return pixelAdjMatr
adj_matrix = getAdjMatrix(im)
$ c $ 解决方案 Python模块/ library NetworkX有一个邻接矩阵实现。它返回一个SciPy的矩阵
导入networkx为nx
导入scipy为sp
g = nx.Graph([(1,1)])
a = nx。 adjacency_matrix(g)
打印a,类型(a)
返回
(0,0)1< class'scipy.sparse.csr.csr_matrix'>
I would like to create a large, weighted adjacency matrix from an image (so lots of vertices... in the order of > 10^5 vertices) in python. Weights between adjacent pixels are color gradients (I take care of this). Doing it by iterating through pixels is very slow... it takes over 4 minutes. :-( Are there any libraries that can do this nicely in reasonable time?
The following is my code which runs very slowly:
def indToCoord(ind, w, h):
x = ind % w
y = (ind - x)/h
return (x,y)
def isAdj(p1, p2, im):
adj = []
w, h = im.size
x1, y1 = p1
x2, y2 = p2
if (x1, y1) == (x2, y2):
return 0
elif abs(x1 - x2) > 1:
return 0
elif abs(y1 - y2) > 1:
return 0
elif abs(x1 - x2) + abs(y1 - y2) >= 2:
return 0
return util.colorGradient(im, p1, p2)
def adjForPixel(pixels, p1, im):
return [isAdj(p1,p2,im) for p2 in pixels]
# The following is the function I use to create an Adjacency Matrix from an image
def getAdjMatrix(im):
width, height = im.size
pixels = [(x,y) for x in xrange(width) for y in xrange(height)]
pixelAdjMatr = [adjForPixel(pixels, p, im) for p in pixels]
return pixelAdjMatr
adj_matrix = getAdjMatrix(im)
Thank you!
解决方案 Python module/library NetworkX has an adjacency matrix implementation. It returns a scipy matrix
import networkx as nx
import scipy as sp
g = nx.Graph([(1,1)])
a = nx.adjacency_matrix(g)
print a, type(a)
returns
(0, 0) 1 <class 'scipy.sparse.csr.csr_matrix'>
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