如何對Numpy的迭代器寫入數據和提取其index

我最開始使用以下代碼：

for iraw, ipro in zip(np.nditer(raw_image), np.nditer(pro_image)):
    ipro= formatfloat(iraw)/65536.0

但行不通，數據根本沒有修改，後改用

for iraw, ipro in zip(np.nditer(raw_image), np.nditer(pro_image, op_flags=['writeonly'])):
    ipro[...] = formatfloat(iraw)/65536.0

提取迭代器index可用以下代碼

it = np.nditer(a, flags=[’multi_index’])

while not it.finished:
... print "%d <%s>" % (it[0], it.multi_index),
... it.iternext()