- 如何列舉多維度陣列索引？
- How to iterate multi-dimensional array indices?
- How to list n-dim(ndim) array indices(index)?
函數實作：
import numpy
'''
moves to the next index from 'current_index'
input:
array: n-dim array
current_index: a tuple consists of each dimension's index, e.g. (1,2,3)
output:
a tuple (the next index), e.g. (1,2,4(=3+1))
'''
def get_next_index(array, current_index):
shape = array.shape
# copies 'current_index', and moves to the next index
next_index = list(current_index)
next_index[array.shape[-1]] += 1
carry = 0
for idx in reversed(range(len(shape))):
next_index[idx] = next_index[idx] + carry
if next_index[idx] < shape[idx]:
break;
else:
carry = int(next_index[idx] / shape[idx])
next_index[idx] = next_index[idx] % shape[idx]
# end-of-if
# end-of-for
return tuple(next_index)
# end-of-def
測試1
a = numpy.array([
['000','001'],['010','011'],['020','021'](/tsungjung411/python-study/wiki/'000','001'],['010','011'],['020','021'),
['100','101'],['110','111'],['120','121'](/tsungjung411/python-study/wiki/'100','101'],['110','111'],['120','121'),
['200','201'],['210','211'],['220','221'](/tsungjung411/python-study/wiki/'200','201'],['210','211'],['220','221'),
['300','301'],['310','311'],['320','321'](/tsungjung411/python-study/wiki/'300','301'],['310','311'],['320','321')
])
print('陣列大小：', a.shape)
print('------------------')
index0 = tuple(numpy.zeros(len(a.shape), dtype=numpy.int32)) # =(0,0,0), start index
index = index0
while True:
print(index)
index = get_next_index(a, index)
if index == index0:
break;
# end-of-if
# end-of-while
執行結果1：
陣列大小： (4, 3, 2)
------------------
(0, 0, 0)
(0, 0, 1)
(0, 1, 0)
(0, 1, 1)
(0, 2, 0)
(0, 2, 1)
(1, 0, 0)
(1, 0, 1)
(1, 1, 0)
(1, 1, 1)
(1, 2, 0)
(1, 2, 1)
(2, 0, 0)
(2, 0, 1)
(2, 1, 0)
(2, 1, 1)
(2, 2, 0)
(2, 2, 1)
(3, 0, 0)
(3, 0, 1)
(3, 1, 0)
(3, 1, 1)
(3, 2, 0)
(3, 2, 1)
測試2：不同起始索引
a = numpy.array([
['000','001'],['010','011'],['020','021'](/tsungjung411/python-study/wiki/'000','001'],['010','011'],['020','021'),
['100','101'],['110','111'],['120','121'](/tsungjung411/python-study/wiki/'100','101'],['110','111'],['120','121'),
['200','201'],['210','211'],['220','221'](/tsungjung411/python-study/wiki/'200','201'],['210','211'],['220','221'),
['300','301'],['310','311'],['320','321'](/tsungjung411/python-study/wiki/'300','301'],['310','311'],['320','321')
])
print('陣列大小：', a.shape)
print('------------------')
index = (0,0,8) # start index
while True:
print(index)
index = get_next_index(a, index)
if index == (0,0,0):
break;
# end-of-if
# end-of-while
執行結果2：
陣列大小： (4, 3, 2)
------------------
(0, 0, 8)
(1, 1, 1)
(1, 2, 0)
(1, 2, 1)
(2, 0, 0)
(2, 0, 1)
(2, 1, 0)
(2, 1, 1)
(2, 2, 0)
(2, 2, 1)
(3, 0, 0)
(3, 0, 1)
(3, 1, 0)
(3, 1, 1)
(3, 2, 0)
(3, 2, 1)