更新:这是 "usecols with parse_dates and names" 的重复问题,但是这个问题先被回答了。
我无论如何都无法让这段代码工作。一旦我去掉 names
参数,它就可以正常工作,但这太愚蠢了。
从一个以空格分隔的文件中,我想要:
- 跳过头部部分
- 导入选定的列
- 给列命名
- 解析两列作为日期
- 使用解析后的日期作为索引
这几乎可以工作:
import panadas as pd
columns = [4, 5, 10, 11, 15, 16, 17, 26, 28, 29]
names = ["DATE","TIME","DLAT", "DLON", "SLAT", "SLON", "SHGT", "HGT", "N", "E"]
ppp_data = pd.read_table(
filename,
delim_whitespace=True, # space delimited
skiprows=8, # skip header rows
header=None, # don't use first row as column names
usecols=columns, # only use selected columns
names=names, # use names for selected columns
parse_dates=[[4,5]], # join date and time columns and parse as date
index_col=0, # use parsed date (now column 0) as index
)
print ppp_data
但是这里是我收到的堆栈跟踪信息:
Traceback (most recent call last):
File "plot_squat_test_pandas.py", line 30, in <module>
index_col=0,
File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 400, in parser_f
return _read(filepath_or_buffer, kwds)
File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 205, in _read
return parser.read()
File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 608, in read
ret = self._engine.read(nrows)
File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 1028, in read
data = self._reader.read(nrows)
File "parser.pyx", line 706, in pandas.parser.TextReader.read (pandas/parser.c:6745)
File "parser.pyx", line 728, in pandas.parser.TextReader._read_low_memory (pandas/parser.c:6964)
File "parser.pyx", line 804, in pandas.parser.TextReader._read_rows (pandas/parser.c:7780)
File "parser.pyx", line 865, in pandas.parser.TextReader._convert_column_data (pandas/parser.c:8512)
File "parser.pyx", line 1105, in pandas.parser.TextReader._get_column_name (pandas/parser.c:11684)
IndexError: list index out of range
如果我注释掉
names=names
参数,那么它就能正常工作。<class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 86281 entries, 2013-10-30 00:00:00 to 2013-10-30 23:59:59
Data columns (total 8 columns):
10 86281 non-null values
11 86281 non-null values
15 86281 non-null values
16 86281 non-null values
17 86281 non-null values
26 86281 non-null values
28 86281 non-null values
29 86281 non-null values
我错过了什么?还是这是pandas的问题,我应该去报告一个错误?
我正在使用python 2.7.3,并且使用pandas,上面的堆栈跟踪来自稳定版本0.12.0。我已经尝试过开发版本0.13.0rc1-119-g2485e09,结果相同(不同的行号)。