擅长:python、mysql、java
<p>如前所述,<code>None</code>是Python中null的等价物。您可以通过以下方法实现:</p>
<pre><code># Keep column headers. Convert numbers to numbers. Empty strings into None (empty "set")
def get_col(col):
if col:
try:
return int(col)
except:
return col
else:
return None
rows = [row.split (',') for row in data.split ('\n')]
# Convert empty columns into None and
rows = [[get_col(col) for col in cols] for cols in rows]
</code></pre>
<p>这将导致<code>rows</code>如下所示:</p>
^{pr2}$
<p>替换get_col函数如下:</p>
<pre><code>def get_col(col):
if col:
return col
else:
return 'null'
</code></pre>
<p>将使您<code>rows</code>如下所示:</p>
<pre><code>[['binary', 'none1', 'Param', 'none2'], ['77', '2601', '54', '55'], ['70', 'null', '25', '224'], ['71', 'null', '33', '38'], etc...
</code></pre>
<p>(使用Python 2.7.9)</p>