我有一个改进的kmeans算法（KPlusPlus），它基于类kmeans。 Detk是从KPlusPlus继承的另一个类。
KPlusPlus类的目标是找出找到kmeans质心的最佳种子（Source）
Detk计算间隙统计量以找到最佳簇数。我从here
找到了此代码# kmeans class
class KMeans():
def __init__(self, K, X=None, N=0):
self.K = K
if X == None:
if N == 0:
raise Exception("If no data is provided, \
a parameter N (number of points) is needed")
else:
self.N = N
self.X = self._init_board_gauss(N, K)
else:
self.X = X
self.N = len(X)
self.mu = None
self.clusters = None
self.method = None
def _init_board_gauss(self, N, k):
n = float(N)/k
X = []
for i in range(k):
c = (random.uniform(-1,1), random.uniform(-1,1))
s = random.uniform(0.05,0.15)
x = []
while len(x) < n:
a,b = np.array([np.random.normal(c[0],s),np.random.normal(c[1],s)])
# Continue drawing points from the distribution in the range [-1,1]
if abs(a) and abs(b)<1:
x.append([a,b])
X.extend(x)
X = np.array(X)[:N]
return X
def plot_board(self):
X = self.X
fig = plt.figure(figsize=(5,5))
plt.xlim(-1,1)
plt.ylim(-1,1)
if self.mu and self.clusters:
mu = self.mu
clus = self.clusters
K = self.K
for m, clu in clus.items():
cs = cm.spectral(1.*m/self.K)
plt.plot(mu[m][0], mu[m][1], 'o', marker='*', \
markersize=12, color=cs)
plt.plot(zip(*clus[m])[0], zip(*clus[m])[1], '.', \
markersize=8, color=cs, alpha=0.5)
else:
plt.plot(zip(*X)[0], zip(*X)[1], '.', alpha=0.5)
if self.method == '++':
tit = 'K-means++'
else:
tit = 'K-means with random initialization'
pars = 'N=%s, K=%s' % (str(self.N), str(self.K))
plt.title('\n'.join([pars, tit]), fontsize=16)
plt.savefig('kpp_N%s_K%s.png' % (str(self.N), str(self.K)), \
bbox_inches='tight', dpi=200)
def _cluster_points(self):
mu = self.mu
clusters = {}
for x in self.X:
bestmukey = min([(i[0], np.linalg.norm(x-mu[i[0]])) \
for i in enumerate(mu)], key=lambda t:t[1])[0]
try:
clusters[bestmukey].append(x)
except KeyError:
clusters[bestmukey] = [x]
self.clusters = clusters
def _reevaluate_centers(self):
clusters = self.clusters
newmu = []
keys = sorted(self.clusters.keys())
for k in keys:
newmu.append(np.mean(clusters[k], axis = 0))
self.mu = newmu
def _has_converged(self):
K = len(self.oldmu)
return(set([tuple(a) for a in self.mu]) == \
set([tuple(a) for a in self.oldmu])\
and len(set([tuple(a) for a in self.mu])) == K)
def find_centers(self,K, method='random'):
self.method = method
X = self.X
K = self.K
self.oldmu = random.sample(X, K)
if method != '++':
# Initialize to K random centers
self.mu = random.sample(X, K)
while not self._has_converged():
self.oldmu = self.mu
# Assign all points in X to clusters
self._cluster_points()
# Reevaluate centers
self._reevaluate_centers()
KPlusPlus类继承kmeans以找到最佳种子
class KPlusPlus(KMeans):
def _dist_from_centers(self):
cent = self.mu
X = self.X
D2 = np.array([min([np.linalg.norm(x-c)**2 for c in cent]) for x in X])
self.D2 = D2
def _choose_next_center(self):
self.probs = self.D2/self.D2.sum()
self.cumprobs = self.probs.cumsum()
r = random.random()
ind = np.where(self.cumprobs >= r)[0][0]
return(self.X[ind])
def init_centers(self,K):
self.K = K
self.mu = random.sample(self.X, 1)
while len(self.mu) < self.K:
self._dist_from_centers()
self.mu.append(self._choose_next_center())
def plot_init_centers(self):
X = self.X
fig = plt.figure(figsize=(5,5))
plt.xlim(-1,1)
plt.ylim(-1,1)
plt.plot(zip(*X)[0], zip(*X)[1], '.', alpha=0.5)
plt.plot(zip(*self.mu)[0], zip(*self.mu)[1], 'ro')
plt.savefig('kpp_init_N%s_K%s.png' % (str(self.N),str(self.K)), \
bbox_inches='tight', dpi=200)
Detk类继承自KPlusPlus，根据差距统计信息找到有效的聚类数
class DetK(KPlusPlus):
def fK(self, thisk, Skm1=0):
X = self.X
Nd = len(X[0])
a = lambda k, Nd: 1 - 3/(4*Nd) if k == 2 else a(k-1, Nd) + (1-a(k-1, Nd))/6
self.find_centers(thisk, method='++')
mu, clusters = self.mu, self.clusters
Sk = sum([np.linalg.norm(mu[i]-c)**2 \
for i in range(thisk) for c in clusters[i]])
if thisk == 1:
fs = 1
elif Skm1 == 0:
fs = 1
else:
fs = Sk/(a(thisk,Nd)*Skm1)
return fs, Sk
def _bounding_box(self):
X = self.X
xmin, xmax = min(X,key=lambda a:a[0])[0], max(X,key=lambda a:a[0])[0]
ymin, ymax = min(X,key=lambda a:a[1])[1], max(X,key=lambda a:a[1])[1]
return (xmin,xmax), (ymin,ymax)
def gap(self, thisk):
X = self.X
(xmin,xmax), (ymin,ymax) = self._bounding_box()
self.init_centers(thisk)
self.find_centers(thisk, method='++')
mu, clusters = self.mu, self.clusters
Wk = np.log(sum([np.linalg.norm(mu[i]-c)**2/(2*len(c)) \
for i in range(thisk) for c in clusters[i]]))
# Create B reference datasets
B = 10
BWkbs = zeros(B)
for i in range(B):
Xb = []
for n in range(len(X)):
Xb.append([random.uniform(xmin,xmax), \
random.uniform(ymin,ymax)])
Xb = np.array(Xb)
kb = DetK(thisk, X=Xb)
kb.init_centers(thisk)
kb.find_centers(thisk, method='++')
ms, cs = kb.mu, kb.clusters
BWkbs[i] = np.log(sum([np.linalg.norm(ms[j]-c)**2/(2*len(c)) \
for j in range(thisk) for c in cs[j]]))
Wkb = sum(BWkbs)/B
sk = np.sqrt(sum((BWkbs-Wkb)**2)/float(B))*np.sqrt(1+1/B)
return Wk, Wkb, sk
def run(self, maxk, which='both'):
ks = range(1,maxk)
fs = zeros(len(ks))
Wks,Wkbs,sks = zeros(len(ks)+1),zeros(len(ks)+1),zeros(len(ks)+1)
# Special case K=1
self.init_centers(1)
if which == 'f':
fs[0], Sk = self.fK(1)
elif which == 'gap':
Wks[0], Wkbs[0], sks[0] = self.gap(1)
else:
fs[0], Sk = self.fK(1)
Wks[0], Wkbs[0], sks[0] = self.gap(1)
# Rest of Ks
for k in ks[1:]:
self.init_centers(k)
if which == 'f':
fs[k-1], Sk = self.fK(k, Skm1=Sk)
elif which == 'gap':
Wks[k-1], Wkbs[k-1], sks[k-1] = self.gap(k)
else:
fs[k-1], Sk = self.fK(k, Skm1=Sk)
Wks[k-1], Wkbs[k-1], sks[k-1] = self.gap(k)
if which == 'f':
self.fs = fs
elif which == 'gap':
G = []
for i in range(len(ks)):
G.append((Wkbs-Wks)[i] - ((Wkbs-Wks)[i+1]-sks[i+1]))
self.G = np.array(G)
else:
self.fs = fs
G = []
for i in range(len(ks)):
G.append((Wkbs-Wks)[i] - ((Wkbs-Wks)[i+1]-sks[i+1]))
self.G = np.array(G)
当我尝试在给定数量的点（locArray）
locArray = np.array(locArrayMaster[counter])
kmeanscluster = DetK(2, X = locArray)
kmeanscluster.run(5)
noClusters[counter] = np.where(kmeanscluster.fs == min(kmeanscluster.fs))[0][0]+ 1
它返回以下错误
File "C:\Users\Anaconda2\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 714, in runfile
execfile(filename, namespace)
File "C:\Users\Anaconda2\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 74, in execfile
exec(compile(scripttext, filename, 'exec'), glob, loc)
File "C:/Users/Documents/SUMOTraffic/kplusplus.py", line 355, in <module>
kmeanscluster.run(5)
File "C:/Users/Documents/SUMOTraffic/kplusplus.py", line 217, in run
Wks[0], Wkbs[0], sks[0] = self.gap(1)
File "C:/Users/Documents/SUMOTraffic/kplusplus.py", line 200, in gap
for j in range(thisk) for c in cs[j]]))
TypeError: 'NoneType' object has no attribute '__getitem__'
感谢您的帮助。
答案 0 :(得分：0)
错误是由于当群集数量仅为1时，kmeans算法无法找到群集中心。因此，不会为此情况创建群集字典。因此，在类TRUE中添加了一行额外的代码，用于检查群集字典的类型是否为class DetK(KPlusPlus):
def fK(self, thisk, Skm1=0):
X = self.X
Nd = len(X[0])
a = lambda k, Nd: 1 - 3/(4*Nd) if k == 2 else a(k-1, Nd) + (1-a(k-1, Nd))/6
self.find_centers(thisk, method='++')
，如果它返回 while type(self.clusters) is not dict:
self.find_centers(thisk, method = '++')
，则会再次重新计算群集中心。
mu, clusters = self.mu, self.clusters
Sk = sum([np.linalg.norm(mu[i]-c)**2 \
for i in range(thisk) for c in clusters[i]])
if thisk == 1:
fs = 1
elif Skm1 == 0:
fs = 1
else:
fs = Sk/(a(thisk,Nd)*Skm1)
return fs, Sk
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