pandas.read_csv 在循环中给出 FileNotFound 错误

Question

pandas.read_csv 在用作单个语句时可以正常工作。但是即使文件存在，它在循环内使用时也会给出 FileNotFoundError。

for filename in os.listdir("./Datasets/pollution"):
    print(filename) # To check which file is under processing
    df = pd.read_csv(filename, sep=",").head(1)

以上几行给出了以下错误。

pollutionData184866.csv <----- The name of the file is printed properly.
Traceback (most recent call last):
  File "/home/parnab/PycharmProjects/FinalYearProject/locationExtractor.py", line 13, in <module>
    df = pd.read_csv(i, sep=",").head(1)
  File "/usr/lib/python3.6/site-packages/pandas/io/parsers.py", line 646, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "/usr/lib/python3.6/site-packages/pandas/io/parsers.py", line 389, in _read
    parser = TextFileReader(filepath_or_buffer, **kwds)
  File "/usr/lib/python3.6/site-packages/pandas/io/parsers.py", line 730, in __init__
    self._make_engine(self.engine)
  File "/usr/lib/python3.6/site-packages/pandas/io/parsers.py", line 923, in _make_engine
    self._engine = CParserWrapper(self.f, **self.options)
  File "/usr/lib/python3.6/site-packages/pandas/io/parsers.py", line 1390, in __init__
    self._reader = _parser.TextReader(src, **kwds)
  File "pandas/parser.pyx", line 373, in pandas.parser.TextReader.__cinit__ (pandas/parser.c:4184)
  File "pandas/parser.pyx", line 667, in pandas.parser.TextReader._setup_parser_source (pandas/parser.c:8449)
FileNotFoundError: File b'pollutionData184866.csv' does not exist

但是当我在做的时候

filename = 'pollutionData184866.csv'
df = pd.read_csv(filename, sep=',')

它工作正常。

我做错了什么？

Answer 1

os.listdir("./Datasets/pollution") returns 没有路径的文件列表，根据路径 "./Datasets/pollution" 您正在解析不是来自当前目录 "." 的 CSV 文件，因此更改glob.glob('./Datasets/pollution/*.csv') 应该可以工作，因为 glob.glob() returns 满足 files/directories 的列表，包括给定路径

演示：

In [19]: os.listdir('d:/temp/.data/629509')
Out[19]:
['AAON_data.csv',
 'AAON_data.png',
 'AAPL_data.csv',
 'AAPL_data.png',
 'AAP_data.csv',
 'AAP_data.png']

In [20]: glob.glob('d:/temp/.data/629509/*.csv')
Out[20]:
['d:/temp/.data/629509\AAON_data.csv',
 'd:/temp/.data/629509\AAPL_data.csv',
 'd:/temp/.data/629509\AAP_data.csv']

pandas.read_csv 在循环中给出 FileNotFound 错误

pandas.read_csv gives FileNotFound error inside a loop

pandas

python-3.6