I have two arrays:
我有两个数组:
>>> import numpy as np
>>> a=np.array([2, 1, 3, 3, 3])
>>> b=np.array([1, 2, 3, 3, 3])
What is the fastest way of comparing these two arrays for equality of elements, regardless of the order?
比较这两个数组以获得元素相等性的最快方法是什么?
EDIT I measured for the execution times of the following functions:
编辑我测量了以下函数的执行时间:
def compare1(): #works only for arrays without redundant elements
a=np.array([1,2,3,5,4])
b=np.array([2,1,3,4,5])
temp=0
for i in a:
temp+=len(np.where(b==i)[0])
if temp==5:
val=True
else:
val=False
return 0
def compare2():
a=np.array([1,2,3,3,3])
b=np.array([2,1,3,3,3])
val=np.all(np.sort(a)==np.sort(b))
return 0
def compare3(): #thx to ODiogoSilva
a=np.array([1,2,3,3,3])
b=np.array([2,1,3,3,3])
val=set(a)==set(b)
return 0
import numpy.lib.arraysetops as aso
def compare4(): #thx to tom10
a=np.array([1,2,3,3,3])
b=np.array([2,1,3,3,3])
val=len(aso.setdiff1d(a,b))==0
return 0
The results are:
结果是:
>>> import timeit
>>> timeit.timeit(compare1,number=1000)
0.0166780948638916
>>> timeit.timeit(compare2,number=1000)
0.016178131103515625
>>> timeit.timeit(compare3,number=1000)
0.008063077926635742
>>> timeit.timeit(compare4,number=1000)
0.03257489204406738
Seems like the "set"-method by ODiogoSilva is the fastest.
似乎是“set”-由ODiogoSilva的方法是最快的。
Do you know other methods that I can test as well?
你知道我还可以测试的其他方法吗?
EDIT2 The runtime above was not the right measure for comparing arrays, as explained in a comment by user2357112.
上面的运行时并不是比较数组的正确度量,正如user2357112在注释中解释的那样。
#test.py
import numpy as np
import numpy.lib.arraysetops as aso
#without duplicates
N=10000
a=np.arange(N,0,step=-2)
b=np.arange(N,0,step=-2)
def compare1():
temp=0
for i in a:
temp+=len(np.where(b==i)[0])
if temp==len(a):
val=True
else:
val=False
return val
def compare2():
val=np.all(np.sort(a)==np.sort(b))
return val
def compare3():
val=set(a)==set(b)
return val
def compare4():
val=len(aso.setdiff1d(a,b))==0
return val
The output is:
的输出是:
>>> from test import *
>>> import timeit
>>> timeit.timeit(compare1,number=1000)
101.16708397865295
>>> timeit.timeit(compare2,number=1000)
0.09285593032836914
>>> timeit.timeit(compare3,number=1000)
1.425955057144165
>>> timeit.timeit(compare4,number=1000)
0.44780397415161133
Now compare2 is the fastest. Is there still a method that could outgun this?
现在比较2是最快的。还有什么方法能比这更有效吗?
2 个解决方案
#1
4
Numpy as a collection of set operations.
Numpy作为一组集操作。
import numpy as np
import numpy.lib.arraysetops as aso
a=np.array([2, 1, 3, 3, 3])
b=np.array([1, 2, 3, 3, 3])
print aso.setdiff1d(a, b)
#2
1
To see if both arrays contain the same kind of elements, in this case [1,2,3], you could do:
要查看两个数组是否包含相同类型的元素,在本例[1,2,3]中,您可以这样做:
import numpy as np
a=np.array([2, 1, 3, 3, 3])
b=np.array([1, 2, 3, 3, 3])
set(a) == set(b)
# True
#1
4
Numpy as a collection of set operations.
Numpy作为一组集操作。
import numpy as np
import numpy.lib.arraysetops as aso
a=np.array([2, 1, 3, 3, 3])
b=np.array([1, 2, 3, 3, 3])
print aso.setdiff1d(a, b)
#2
1
To see if both arrays contain the same kind of elements, in this case [1,2,3], you could do:
要查看两个数组是否包含相同类型的元素,在本例[1,2,3]中,您可以这样做:
import numpy as np
a=np.array([2, 1, 3, 3, 3])
b=np.array([1, 2, 3, 3, 3])
set(a) == set(b)
# True