回答此问题可获得 20 贡献值,回答如果被采纳可获得 50 分。
<p>所以我从NOAA读取了一个车站代码csv文件,如下所示:</p>
<pre><code>"USAF","WBAN","STATION NAME","CTRY","FIPS","STATE","CALL","LAT","LON","ELEV(.1M)","BEGIN","END"
"006852","99999","SENT","SW","SZ","","","+46817","+010350","+14200","",""
"007005","99999","CWOS 07005","","","","","-99999","-999999","-99999","20120127","20120127"
</code></pre>
<p>前两列包含气象站的代码,有时它们有前导零。当pandas在不指定数据类型的情况下导入它们时,它们会变成整数。这没什么大不了的,因为我可以循环遍历数据帧索引,并用类似<code>"%06d" % i</code>的内容替换它们,因为它们总是6位数字,但是你知道。。。那是懒人的方式。</p>
<p>使用以下代码获取csv:</p>
<pre><code>file = urllib.urlopen(r"ftp://ftp.ncdc.noaa.gov/pub/data/inventories/ISH-HISTORY.CSV")
output = open('Station Codes.csv','wb')
output.write(file.read())
output.close()
</code></pre>
<p>一切都很好,但是当我试着用这个读的时候:</p>
<pre><code>import pandas as pd
df = pd.io.parsers.read_csv("Station Codes.csv",dtype={'USAF': np.str, 'WBAN': np.str})
</code></pre>
<p>或者</p>
<pre><code>import pandas as pd
df = pd.io.parsers.read_csv("Station Codes.csv",dtype={'USAF': str, 'WBAN': str})
</code></pre>
<p>我收到一条令人讨厌的错误信息:</p>
<pre><code>File "C:\Python27\lib\site-packages\pandas-0.11.0-py2.7-win32.egg\pandas\io\parsers.py", line 401, in parser
_f
return _read(filepath_or_buffer, kwds)
File "C:\Python27\lib\site-packages\pandas-0.11.0-py2.7-win32.egg\pandas\io\parsers.py", line 216, in _read
return parser.read()
File "C:\Python27\lib\site-packages\pandas-0.11.0-py2.7-win32.egg\pandas\io\parsers.py", line 633, in read
ret = self._engine.read(nrows)
File "C:\Python27\lib\site-packages\pandas-0.11.0-py2.7-win32.egg\pandas\io\parsers.py", line 957, in read
data = self._reader.read(nrows)
File "parser.pyx", line 654, in pandas._parser.TextReader.read (pandas\src\parser.c:5931)
File "parser.pyx", line 676, in pandas._parser.TextReader._read_low_memory (pandas\src\parser.c:6148)
File "parser.pyx", line 752, in pandas._parser.TextReader._read_rows (pandas\src\parser.c:6962)
File "parser.pyx", line 837, in pandas._parser.TextReader._convert_column_data (pandas\src\parser.c:7898)
File "parser.pyx", line 887, in pandas._parser.TextReader._convert_tokens (pandas\src\parser.c:8483)
File "parser.pyx", line 953, in pandas._parser.TextReader._convert_with_dtype (pandas\src\parser.c:9535)
File "parser.pyx", line 1283, in pandas._parser._to_fw_string (pandas\src\parser.c:14616)
TypeError: data type not understood
</code></pre>
<p>这是一个相当大的csv(31k行),所以也许这与它有关?</p>