def test_from_delayed():
from dask.delayed import delayed
a, b, c = delayed([1, 2, 3]), delayed([4, 5, 6]), delayed([7, 8, 9])
bb = from_delayed([a, b, c])
assert bb.name == from_delayed([a, b, c]).name
assert isinstance(bb, Bag)
assert list(bb) == [1, 2, 3, 4, 5, 6, 7, 8, 9]
asum_value = delayed(lambda X: sum(X))(a)
asum_item = db.Item.from_delayed(asum_value)
assert asum_value.compute() == asum_item.compute() == 6
def test_from_delayed():
from dask.delayed import value, do
a, b, c = value([1, 2, 3]), value([4, 5, 6]), value([7, 8, 9])
bb = from_delayed([a, b, c])
assert bb.name == from_delayed([a, b, c]).name
assert isinstance(bb, Bag)
assert list(bb) == [1, 2, 3, 4, 5, 6, 7, 8, 9]
asum_value = do(lambda X: sum(X))(a)
asum_item = db.Item.from_delayed(asum_value)
assert asum_value.compute() == asum_item.compute() == 6
def read_text(
urlpath,
blocksize=None,
compression="infer",
encoding=system_encoding,
errors="strict",
linedelimiter=None,
collection=True,
storage_options=None,
files_per_partition=None,
include_path=False,
):
"""Read lines from text files
Parameters
----------
urlpath : string or list
Absolute or relative filepath(s). Prefix with a protocol like ``s3://``
to read from alternative filesystems. To read from multiple files you
can pass a globstring or a list of paths, with the caveat that they
must all have the same protocol.
blocksize: None, int, or str
Size (in bytes) to cut up larger files. Streams by default.
Can be ``None`` for streaming, an integer number of bytes, or a string
like "128MiB"
compression: string
Compression format like 'gzip' or 'xz'. Defaults to 'infer'
encoding: string
errors: string
linedelimiter: string or None
collection: bool, optional
Return dask.bag if True, or list of delayed values if false
storage_options: dict
Extra options that make sense to a particular storage connection, e.g.
host, port, username, password, etc.
files_per_partition: None or int
If set, group input files into partitions of the requested size,
instead of one partition per file. Mutually exclusive with blocksize.
include_path: bool
Whether or not to include the path in the bag.
If true, elements are tuples of (line, path).
Default is False.
Examples
--------
>>> b = read_text('myfiles.1.txt') # doctest: +SKIP
>>> b = read_text('myfiles.*.txt') # doctest: +SKIP
>>> b = read_text('myfiles.*.txt.gz') # doctest: +SKIP
>>> b = read_text('s3://bucket/myfiles.*.txt') # doctest: +SKIP
>>> b = read_text('s3://key:secret@bucket/myfiles.*.txt') # doctest: +SKIP
>>> b = read_text('hdfs://namenode.example.com/myfiles.*.txt') # doctest: +SKIP
Parallelize a large file by providing the number of uncompressed bytes to
load into each partition.
>>> b = read_text('largefile.txt', blocksize='10MB') # doctest: +SKIP
Get file paths of the bag by setting include_path=True
>>> b = read_text('myfiles.*.txt', include_path=True) # doctest: +SKIP
>>> b.take(1) # doctest: +SKIP
(('first line of the first file', '/home/dask/myfiles.0.txt'),)
Returns
-------
dask.bag.Bag or list
dask.bag.Bag if collection is True or list of Delayed lists otherwise.
See Also
--------
from_sequence: Build bag from Python sequence
"""
if blocksize is not None and files_per_partition is not None:
raise ValueError(
"Only one of blocksize or files_per_partition can be set")
if isinstance(blocksize, str):
blocksize = parse_bytes(blocksize)
if blocksize is None:
if linedelimiter in [None, "", "\n", "\r", "\r\n"]:
newline = linedelimiter
linedelimiter = None
else:
newline = ""
files = open_files(
urlpath,
mode="rt",
encoding=encoding,
errors=errors,
compression=compression,
newline=newline,
**(storage_options or {}),
)
if files_per_partition is None:
blocks = [
delayed(list)(delayed(
partial(file_to_blocks,
include_path,
delimiter=linedelimiter))(fil)) for fil in files
]
else:
blocks = []
for start in range(0, len(files), files_per_partition):
block_files = files[start:(start + files_per_partition)]
block_lines = delayed(concat)(delayed(map)(
partial(file_to_blocks,
include_path,
delimiter=linedelimiter),
block_files,
))
blocks.append(block_lines)
else:
# special case for linedelimiter=None: we will need to split on an actual bytestring
# and the line reader will then use "universal" mode. Just as well that \r\n and \n
# will both work (thankfully \r for MacOS is no longer a thing)
o = read_bytes(
urlpath,
delimiter=linedelimiter.encode()
if linedelimiter is not None else b"\n",
blocksize=blocksize,
sample=False,
compression=compression,
include_path=include_path,
**(storage_options or {}),
)
raw_blocks = o[1]
blocks = [
delayed(decode)(b, encoding, errors, linedelimiter)
for b in concat(raw_blocks)
]
if include_path:
paths = list(
concat([[path] * len(raw_blocks[i])
for i, path in enumerate(o[2])]))
blocks = [
delayed(attach_path)(entry, path)
for entry, path in zip(blocks, paths)
]
if not blocks:
raise ValueError("No files found", urlpath)
if collection:
blocks = from_delayed(blocks)
return blocks
