craftbeerpi4-pione/venv/lib/python3.8/site-packages/pandas/io/formats/csvs.py
2021-01-30 22:29:33 +01:00

362 lines
11 KiB
Python

"""
Module for formatting output data into CSV files.
"""
import csv as csvlib
from io import StringIO
import os
from typing import Hashable, List, Mapping, Optional, Sequence, Union
import warnings
from zipfile import ZipFile
import numpy as np
from pandas._libs import writers as libwriters
from pandas._typing import FilePathOrBuffer
from pandas.core.dtypes.generic import (
ABCDatetimeIndex,
ABCIndexClass,
ABCMultiIndex,
ABCPeriodIndex,
)
from pandas.core.dtypes.missing import notna
from pandas.io.common import (
get_compression_method,
get_filepath_or_buffer,
get_handle,
infer_compression,
)
class CSVFormatter:
def __init__(
self,
obj,
path_or_buf: Optional[FilePathOrBuffer[str]] = None,
sep: str = ",",
na_rep: str = "",
float_format: Optional[str] = None,
cols=None,
header: Union[bool, Sequence[Hashable]] = True,
index: bool = True,
index_label: Optional[Union[bool, Hashable, Sequence[Hashable]]] = None,
mode: str = "w",
encoding: Optional[str] = None,
errors: str = "strict",
compression: Union[str, Mapping[str, str], None] = "infer",
quoting: Optional[int] = None,
line_terminator="\n",
chunksize: Optional[int] = None,
quotechar='"',
date_format: Optional[str] = None,
doublequote: bool = True,
escapechar: Optional[str] = None,
decimal=".",
):
self.obj = obj
if path_or_buf is None:
path_or_buf = StringIO()
# Extract compression mode as given, if dict
compression, self.compression_args = get_compression_method(compression)
self.path_or_buf, _, _, self.should_close = get_filepath_or_buffer(
path_or_buf, encoding=encoding, compression=compression, mode=mode
)
self.sep = sep
self.na_rep = na_rep
self.float_format = float_format
self.decimal = decimal
self.header = header
self.index = index
self.index_label = index_label
self.mode = mode
if encoding is None:
encoding = "utf-8"
self.encoding = encoding
self.errors = errors
self.compression = infer_compression(self.path_or_buf, compression)
if quoting is None:
quoting = csvlib.QUOTE_MINIMAL
self.quoting = quoting
if quoting == csvlib.QUOTE_NONE:
# prevents crash in _csv
quotechar = None
self.quotechar = quotechar
self.doublequote = doublequote
self.escapechar = escapechar
self.line_terminator = line_terminator or os.linesep
self.date_format = date_format
self.has_mi_columns = isinstance(obj.columns, ABCMultiIndex)
# validate mi options
if self.has_mi_columns:
if cols is not None:
raise TypeError("cannot specify cols with a MultiIndex on the columns")
if cols is not None:
if isinstance(cols, ABCIndexClass):
cols = cols.to_native_types(
na_rep=na_rep,
float_format=float_format,
date_format=date_format,
quoting=self.quoting,
)
else:
cols = list(cols)
self.obj = self.obj.loc[:, cols]
# update columns to include possible multiplicity of dupes
# and make sure sure cols is just a list of labels
cols = self.obj.columns
if isinstance(cols, ABCIndexClass):
cols = cols.to_native_types(
na_rep=na_rep,
float_format=float_format,
date_format=date_format,
quoting=self.quoting,
)
else:
cols = list(cols)
# save it
self.cols = cols
# preallocate data 2d list
ncols = self.obj.shape[-1]
self.data = [None] * ncols
if chunksize is None:
chunksize = (100000 // (len(self.cols) or 1)) or 1
self.chunksize = int(chunksize)
self.data_index = obj.index
if (
isinstance(self.data_index, (ABCDatetimeIndex, ABCPeriodIndex))
and date_format is not None
):
from pandas import Index
self.data_index = Index(
[x.strftime(date_format) if notna(x) else "" for x in self.data_index]
)
self.nlevels = getattr(self.data_index, "nlevels", 1)
if not index:
self.nlevels = 0
def save(self) -> None:
"""
Create the writer & save.
"""
# GH21227 internal compression is not used when file-like passed.
if self.compression and hasattr(self.path_or_buf, "write"):
warnings.warn(
"compression has no effect when passing file-like object as input.",
RuntimeWarning,
stacklevel=2,
)
# when zip compression is called.
is_zip = isinstance(self.path_or_buf, ZipFile) or (
not hasattr(self.path_or_buf, "write") and self.compression == "zip"
)
if is_zip:
# zipfile doesn't support writing string to archive. uses string
# buffer to receive csv writing and dump into zip compression
# file handle. GH21241, GH21118
f = StringIO()
close = False
elif hasattr(self.path_or_buf, "write"):
f = self.path_or_buf
close = False
else:
f, handles = get_handle(
self.path_or_buf,
self.mode,
encoding=self.encoding,
errors=self.errors,
compression=dict(self.compression_args, method=self.compression),
)
close = True
try:
# Note: self.encoding is irrelevant here
self.writer = csvlib.writer(
f,
lineterminator=self.line_terminator,
delimiter=self.sep,
quoting=self.quoting,
doublequote=self.doublequote,
escapechar=self.escapechar,
quotechar=self.quotechar,
)
self._save()
finally:
if is_zip:
# GH17778 handles zip compression separately.
buf = f.getvalue()
if hasattr(self.path_or_buf, "write"):
self.path_or_buf.write(buf)
else:
compression = dict(self.compression_args, method=self.compression)
f, handles = get_handle(
self.path_or_buf,
self.mode,
encoding=self.encoding,
errors=self.errors,
compression=compression,
)
f.write(buf)
close = True
if close:
f.close()
for _fh in handles:
_fh.close()
elif self.should_close:
f.close()
def _save_header(self):
writer = self.writer
obj = self.obj
index_label = self.index_label
cols = self.cols
has_mi_columns = self.has_mi_columns
header = self.header
encoded_labels: List[str] = []
has_aliases = isinstance(header, (tuple, list, np.ndarray, ABCIndexClass))
if not (has_aliases or self.header):
return
if has_aliases:
if len(header) != len(cols):
raise ValueError(
f"Writing {len(cols)} cols but got {len(header)} aliases"
)
else:
write_cols = header
else:
write_cols = cols
if self.index:
# should write something for index label
if index_label is not False:
if index_label is None:
if isinstance(obj.index, ABCMultiIndex):
index_label = []
for i, name in enumerate(obj.index.names):
if name is None:
name = ""
index_label.append(name)
else:
index_label = obj.index.name
if index_label is None:
index_label = [""]
else:
index_label = [index_label]
elif not isinstance(
index_label, (list, tuple, np.ndarray, ABCIndexClass)
):
# given a string for a DF with Index
index_label = [index_label]
encoded_labels = list(index_label)
else:
encoded_labels = []
if not has_mi_columns or has_aliases:
encoded_labels += list(write_cols)
writer.writerow(encoded_labels)
else:
# write out the mi
columns = obj.columns
# write out the names for each level, then ALL of the values for
# each level
for i in range(columns.nlevels):
# we need at least 1 index column to write our col names
col_line = []
if self.index:
# name is the first column
col_line.append(columns.names[i])
if isinstance(index_label, list) and len(index_label) > 1:
col_line.extend([""] * (len(index_label) - 1))
col_line.extend(columns._get_level_values(i))
writer.writerow(col_line)
# Write out the index line if it's not empty.
# Otherwise, we will print out an extraneous
# blank line between the mi and the data rows.
if encoded_labels and set(encoded_labels) != {""}:
encoded_labels.extend([""] * len(columns))
writer.writerow(encoded_labels)
def _save(self) -> None:
self._save_header()
nrows = len(self.data_index)
# write in chunksize bites
chunksize = self.chunksize
chunks = int(nrows / chunksize) + 1
for i in range(chunks):
start_i = i * chunksize
end_i = min((i + 1) * chunksize, nrows)
if start_i >= end_i:
break
self._save_chunk(start_i, end_i)
def _save_chunk(self, start_i: int, end_i: int) -> None:
data_index = self.data_index
# create the data for a chunk
slicer = slice(start_i, end_i)
df = self.obj.iloc[slicer]
blocks = df._mgr.blocks
for i in range(len(blocks)):
b = blocks[i]
d = b.to_native_types(
na_rep=self.na_rep,
float_format=self.float_format,
decimal=self.decimal,
date_format=self.date_format,
quoting=self.quoting,
)
for col_loc, col in zip(b.mgr_locs, d):
# self.data is a preallocated list
self.data[col_loc] = col
ix = data_index.to_native_types(
slicer=slicer,
na_rep=self.na_rep,
float_format=self.float_format,
decimal=self.decimal,
date_format=self.date_format,
quoting=self.quoting,
)
libwriters.write_csv_rows(self.data, ix, self.nlevels, self.cols, self.writer)