擅长:python、mysql、java
<p>看,布尔索引的力量!!!在</p>
<pre><code>def shift_nans(arr) :
while True:
nan_mask = np.isnan(arr)
write_mask = nan_mask[1:, :-1]
read_mask = nan_mask[:-1, 1:]
write_mask &= ~read_mask
if not np.any(write_mask):
return arr
arr[1:, :-1][write_mask] = arr[:-1, 1:][write_mask]
</code></pre>
<p>我认为这个名字是不言而喻的。正确的切片是一件痛苦的事,但它似乎奏效了:</p>
^{pr2}$
<p>时间安排:</p>
<pre><code>tmp1 = np.random.uniform(-10, 20, (1e4, 1e2))
nan_idx = np.random.randint(30, 1e4 - 1,1e4)
tmp1[nan_idx] = np.nan
tmp1 = tmp.copy()
import timeit
t1 = timeit.timeit(stmt='shift_nans(tmp)',
setup='from __main__ import tmp, shift_nans',
number=1)
t2 = timeit.timeit(stmt='shift_time(tmp1)', # Ophion's code
setup='from __main__ import tmp1, shift_time',
number=1)
In [242]: t1, t2
Out[242]: (0.12696346416487359, 0.3427293070417363)
</code></pre>