"""Common IO api utilities""" import os import csv import codecs import mmap from contextlib import contextmanager, closing import zipfile from pandas.compat import StringIO, BytesIO, string_types, text_type from pandas import compat from pandas.io.formats.printing import pprint_thing import pandas.core.common as com from pandas.core.dtypes.common import is_number, is_file_like # compat from pandas.errors import (ParserError, DtypeWarning, # noqa EmptyDataError, ParserWarning) # gh-12665: Alias for now and remove later. CParserError = ParserError # common NA values # no longer excluding inf representations # '1.#INF','-1.#INF', '1.#INF000000', _NA_VALUES = set([ '-1.#IND', '1.#QNAN', '1.#IND', '-1.#QNAN', '#N/A N/A', '#N/A', 'N/A', 'n/a', 'NA', '#NA', 'NULL', 'null', 'NaN', '-NaN', 'nan', '-nan', '' ]) if compat.PY3: from urllib.request import urlopen, pathname2url _urlopen = urlopen from urllib.parse import urlparse as parse_url from urllib.parse import (uses_relative, uses_netloc, uses_params, urlencode, urljoin) from urllib.error import URLError from http.client import HTTPException # noqa else: from urllib2 import urlopen as _urlopen from urllib import urlencode, pathname2url # noqa from urlparse import urlparse as parse_url from urlparse import uses_relative, uses_netloc, uses_params, urljoin from urllib2 import URLError # noqa from httplib import HTTPException # noqa from contextlib import contextmanager, closing # noqa from functools import wraps # noqa # @wraps(_urlopen) @contextmanager def urlopen(*args, **kwargs): with closing(_urlopen(*args, **kwargs)) as f: yield f _VALID_URLS = set(uses_relative + uses_netloc + uses_params) _VALID_URLS.discard('') class BaseIterator(object): """Subclass this and provide a "__next__()" method to obtain an iterator. Useful only when the object being iterated is non-reusable (e.g. OK for a parser, not for an in-memory table, yes for its iterator).""" def __iter__(self): return self def __next__(self): raise com.AbstractMethodError(self) if not compat.PY3: BaseIterator.next = lambda self: self.__next__() def _is_url(url): """Check to see if a URL has a valid protocol. Parameters ---------- url : str or unicode Returns ------- isurl : bool If `url` has a valid protocol return True otherwise False. """ try: return parse_url(url).scheme in _VALID_URLS except: return False def _expand_user(filepath_or_buffer): """Return the argument with an initial component of ~ or ~user replaced by that user's home directory. Parameters ---------- filepath_or_buffer : object to be converted if possible Returns ------- expanded_filepath_or_buffer : an expanded filepath or the input if not expandable """ if isinstance(filepath_or_buffer, string_types): return os.path.expanduser(filepath_or_buffer) return filepath_or_buffer def _validate_header_arg(header): if isinstance(header, bool): raise TypeError("Passing a bool to header is invalid. " "Use header=None for no header or " "header=int or list-like of ints to specify " "the row(s) making up the column names") def _stringify_path(filepath_or_buffer): """Attempt to convert a path-like object to a string. Parameters ---------- filepath_or_buffer : object to be converted Returns ------- str_filepath_or_buffer : maybe a string version of the object Notes ----- Objects supporting the fspath protocol (python 3.6+) are coerced according to its __fspath__ method. For backwards compatibility with older pythons, pathlib.Path and py.path objects are specially coerced. Any other object is passed through unchanged, which includes bytes, strings, buffers, or anything else that's not even path-like. """ try: import pathlib _PATHLIB_INSTALLED = True except ImportError: _PATHLIB_INSTALLED = False try: from py.path import local as LocalPath _PY_PATH_INSTALLED = True except ImportError: _PY_PATH_INSTALLED = False if hasattr(filepath_or_buffer, '__fspath__'): return filepath_or_buffer.__fspath__() if _PATHLIB_INSTALLED and isinstance(filepath_or_buffer, pathlib.Path): return text_type(filepath_or_buffer) if _PY_PATH_INSTALLED and isinstance(filepath_or_buffer, LocalPath): return filepath_or_buffer.strpath return filepath_or_buffer def is_s3_url(url): """Check for an s3, s3n, or s3a url""" try: return parse_url(url).scheme in ['s3', 's3n', 's3a'] except: # noqa return False def get_filepath_or_buffer(filepath_or_buffer, encoding=None, compression=None, mode=None): """ If the filepath_or_buffer is a url, translate and return the buffer. Otherwise passthrough. Parameters ---------- filepath_or_buffer : a url, filepath (str, py.path.local or pathlib.Path), or buffer encoding : the encoding to use to decode py3 bytes, default is 'utf-8' mode : str, optional Returns ------- tuple of ({a filepath_ or buffer or S3File instance}, encoding, str, compression, str, should_close, bool) """ filepath_or_buffer = _stringify_path(filepath_or_buffer) if _is_url(filepath_or_buffer): req = _urlopen(filepath_or_buffer) content_encoding = req.headers.get('Content-Encoding', None) if content_encoding == 'gzip': # Override compression based on Content-Encoding header compression = 'gzip' reader = BytesIO(req.read()) req.close() return reader, encoding, compression, True if is_s3_url(filepath_or_buffer): from pandas.io import s3 return s3.get_filepath_or_buffer(filepath_or_buffer, encoding=encoding, compression=compression, mode=mode) if isinstance(filepath_or_buffer, (compat.string_types, compat.binary_type, mmap.mmap)): return _expand_user(filepath_or_buffer), None, compression, False if not is_file_like(filepath_or_buffer): msg = "Invalid file path or buffer object type: {_type}" raise ValueError(msg.format(_type=type(filepath_or_buffer))) return filepath_or_buffer, None, compression, False def file_path_to_url(path): """ converts an absolute native path to a FILE URL. Parameters ---------- path : a path in native format Returns ------- a valid FILE URL """ return urljoin('file:', pathname2url(path)) _compression_to_extension = { 'gzip': '.gz', 'bz2': '.bz2', 'zip': '.zip', 'xz': '.xz', } def _infer_compression(filepath_or_buffer, compression): """ Get the compression method for filepath_or_buffer. If compression='infer', the inferred compression method is returned. Otherwise, the input compression method is returned unchanged, unless it's invalid, in which case an error is raised. Parameters ---------- filepath_or_buf : a path (str) or buffer compression : str or None the compression method including None for no compression and 'infer' Returns ------- string or None : compression method Raises ------ ValueError on invalid compression specified """ # No compression has been explicitly specified if compression is None: return None # Infer compression if compression == 'infer': # Convert all path types (e.g. pathlib.Path) to strings filepath_or_buffer = _stringify_path(filepath_or_buffer) if not isinstance(filepath_or_buffer, compat.string_types): # Cannot infer compression of a buffer, assume no compression return None # Infer compression from the filename/URL extension for compression, extension in _compression_to_extension.items(): if filepath_or_buffer.endswith(extension): return compression return None # Compression has been specified. Check that it's valid if compression in _compression_to_extension: return compression msg = 'Unrecognized compression type: {}'.format(compression) valid = ['infer', None] + sorted(_compression_to_extension) msg += '\nValid compression types are {}'.format(valid) raise ValueError(msg) def _get_handle(path_or_buf, mode, encoding=None, compression=None, memory_map=False, is_text=True): """ Get file handle for given path/buffer and mode. Parameters ---------- path_or_buf : a path (str) or buffer mode : str mode to open path_or_buf with encoding : str or None compression : str or None Supported compression protocols are gzip, bz2, zip, and xz memory_map : boolean, default False See parsers._parser_params for more information. is_text : boolean, default True whether file/buffer is in text format (csv, json, etc.), or in binary mode (pickle, etc.) Returns ------- f : file-like A file-like object handles : list of file-like objects A list of file-like object that were opened in this function. """ try: from s3fs import S3File need_text_wrapping = (BytesIO, S3File) except ImportError: need_text_wrapping = (BytesIO,) handles = list() f = path_or_buf # Convert pathlib.Path/py.path.local or string path_or_buf = _stringify_path(path_or_buf) is_path = isinstance(path_or_buf, compat.string_types) if compression: if compat.PY2 and not is_path and encoding: msg = 'compression with encoding is not yet supported in Python 2' raise ValueError(msg) # GZ Compression if compression == 'gzip': import gzip if is_path: f = gzip.open(path_or_buf, mode) else: f = gzip.GzipFile(fileobj=path_or_buf) # BZ Compression elif compression == 'bz2': import bz2 if is_path: f = bz2.BZ2File(path_or_buf, mode) elif compat.PY2: # Python 2's bz2 module can't take file objects, so have to # run through decompress manually f = StringIO(bz2.decompress(path_or_buf.read())) path_or_buf.close() else: f = bz2.BZ2File(path_or_buf) # ZIP Compression elif compression == 'zip': zf = BytesZipFile(path_or_buf, mode) if zf.mode == 'w': f = zf elif zf.mode == 'r': zip_names = zf.namelist() if len(zip_names) == 1: f = zf.open(zip_names.pop()) elif len(zip_names) == 0: raise ValueError('Zero files found in ZIP file {}' .format(path_or_buf)) else: raise ValueError('Multiple files found in ZIP file.' ' Only one file per ZIP: {}' .format(zip_names)) # XZ Compression elif compression == 'xz': lzma = compat.import_lzma() f = lzma.LZMAFile(path_or_buf, mode) # Unrecognized Compression else: msg = 'Unrecognized compression type: {}'.format(compression) raise ValueError(msg) handles.append(f) elif is_path: if compat.PY2: # Python 2 f = open(path_or_buf, mode) elif encoding: # Python 3 and encoding f = open(path_or_buf, mode, encoding=encoding) elif is_text: # Python 3 and no explicit encoding f = open(path_or_buf, mode, errors='replace') else: # Python 3 and binary mode f = open(path_or_buf, mode) handles.append(f) # in Python 3, convert BytesIO or fileobjects passed with an encoding if compat.PY3 and is_text and\ (compression or isinstance(f, need_text_wrapping)): from io import TextIOWrapper f = TextIOWrapper(f, encoding=encoding) handles.append(f) if memory_map and hasattr(f, 'fileno'): try: g = MMapWrapper(f) f.close() f = g except Exception: # we catch any errors that may have occurred # because that is consistent with the lower-level # functionality of the C engine (pd.read_csv), so # leave the file handler as is then pass return f, handles class BytesZipFile(zipfile.ZipFile, BytesIO): """ Wrapper for standard library class ZipFile and allow the returned file-like handle to accept byte strings via `write` method. BytesIO provides attributes of file-like object and ZipFile.writestr writes bytes strings into a member of the archive. """ # GH 17778 def __init__(self, file, mode, compression=zipfile.ZIP_DEFLATED, **kwargs): if mode in ['wb', 'rb']: mode = mode.replace('b', '') super(BytesZipFile, self).__init__(file, mode, compression, **kwargs) def write(self, data): super(BytesZipFile, self).writestr(self.filename, data) @property def closed(self): return self.fp is None class MMapWrapper(BaseIterator): """ Wrapper for the Python's mmap class so that it can be properly read in by Python's csv.reader class. Parameters ---------- f : file object File object to be mapped onto memory. Must support the 'fileno' method or have an equivalent attribute """ def __init__(self, f): self.mmap = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) def __getattr__(self, name): return getattr(self.mmap, name) def __iter__(self): return self def __next__(self): newline = self.mmap.readline() # readline returns bytes, not str, in Python 3, # but Python's CSV reader expects str, so convert # the output to str before continuing if compat.PY3: newline = compat.bytes_to_str(newline) # mmap doesn't raise if reading past the allocated # data but instead returns an empty string, so raise # if that is returned if newline == '': raise StopIteration return newline if not compat.PY3: MMapWrapper.next = lambda self: self.__next__() class UTF8Recoder(BaseIterator): """ Iterator that reads an encoded stream and reencodes the input to UTF-8 """ def __init__(self, f, encoding): self.reader = codecs.getreader(encoding)(f) def read(self, bytes=-1): return self.reader.read(bytes).encode("utf-8") def readline(self): return self.reader.readline().encode("utf-8") def next(self): return next(self.reader).encode("utf-8") if compat.PY3: # pragma: no cover def UnicodeReader(f, dialect=csv.excel, encoding="utf-8", **kwds): # ignore encoding return csv.reader(f, dialect=dialect, **kwds) def UnicodeWriter(f, dialect=csv.excel, encoding="utf-8", **kwds): return csv.writer(f, dialect=dialect, **kwds) else: class UnicodeReader(BaseIterator): """ A CSV reader which will iterate over lines in the CSV file "f", which is encoded in the given encoding. On Python 3, this is replaced (below) by csv.reader, which handles unicode. """ def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds): f = UTF8Recoder(f, encoding) self.reader = csv.reader(f, dialect=dialect, **kwds) def __next__(self): row = next(self.reader) return [compat.text_type(s, "utf-8") for s in row] class UnicodeWriter(object): """ A CSV writer which will write rows to CSV file "f", which is encoded in the given encoding. """ def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds): # Redirect output to a queue self.queue = StringIO() self.writer = csv.writer(self.queue, dialect=dialect, **kwds) self.stream = f self.encoder = codecs.getincrementalencoder(encoding)() self.quoting = kwds.get("quoting", None) def writerow(self, row): def _check_as_is(x): return (self.quoting == csv.QUOTE_NONNUMERIC and is_number(x)) or isinstance(x, str) row = [x if _check_as_is(x) else pprint_thing(x).encode("utf-8") for x in row] self.writer.writerow([s for s in row]) # Fetch UTF-8 output from the queue ... data = self.queue.getvalue() data = data.decode("utf-8") # ... and re-encode it into the target encoding data = self.encoder.encode(data) # write to the target stream self.stream.write(data) # empty queue self.queue.truncate(0) def writerows(self, rows): def _check_as_is(x): return (self.quoting == csv.QUOTE_NONNUMERIC and is_number(x)) or isinstance(x, str) for i, row in enumerate(rows): rows[i] = [x if _check_as_is(x) else pprint_thing(x).encode("utf-8") for x in row] self.writer.writerows([[s for s in row] for row in rows]) # Fetch UTF-8 output from the queue ... data = self.queue.getvalue() data = data.decode("utf-8") # ... and re-encode it into the target encoding data = self.encoder.encode(data) # write to the target stream self.stream.write(data) # empty queue self.queue.truncate(0)