# unique函数

`numpy.unique(arr, return_index, return_inverse, return_counts)`

Sr.No.Parameter & 描述
1

arr

2

return_index

3

return_inverse

4

return_counts

```import numpy as np
a=np.array([5,2,6,2,7,5,6,8,2,9])

print 'First array:'
print a
print '\n'

print 'Unique values of first array:'
u=np.unique(a)
print u
print '\n'

print 'Unique array and Indices array:'
u,indices=np.unique(a, return_index=True)
print indices
print '\n'

print 'We can see each number corresponds to index in original array:'
print a
print '\n'

print 'Indices of unique array:'
u,indices=np.unique(a,return_inverse=True)
print u
print '\n'

print 'Indices are:'
print indices
print '\n'

print 'Reconstruct the original array using indices:'
print u[indices]
print '\n'

print 'Return the count of repetitions of unique elements:'
u,indices=np.unique(a,return_counts=True)
print u
print indices```

```First array:
[5 2 6 2 7 5 6 8 2 9]

Unique values of first array:
[2 5 6 7 8 9]

Unique array and Indices array:
[1 0 2 4 7 9]

We can see each number corresponds to index in original array:
[5 2 6 2 7 5 6 8 2 9]

Indices of unique array:
[2 5 6 7 8 9]

Indices are:
[1 0 2 0 3 1 2 4 0 5]

Reconstruct the original array using indices:
[5 2 6 2 7 5 6 8 2 9]

Return the count of repetitions of unique elements:
[2 5 6 7 8 9]
[3 2 2 1 1 1]```

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