[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2021-10-03 Thread Laurent Gautier 


Laurent Gautier  added the comment:

Bump.

I am still stumbling on that issue. I have a workaround by importing numpy but 
that's a rather large dependency for that one little thing.

I see that the related issue https://bugs.python.org/issue35845 opened later 
has later discussion entries.

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2019-08-31 Thread Laurent Gautier 


Laurent Gautier  added the comment:

Bump.

Is there anything I could do to move this forward (as in write and submit a 
patch for review) ?

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2019-02-02 Thread Laurent Gautier 


Laurent Gautier  added the comment:

> General support for strides in cast(), i.e. a zero-copy view for
> non-contiguous arrays does not seem possible because buf.ptr is
> moved around. Even NumPy does not support that:

I'd be happy enough with zero-copy `cast()` of f-continguous arrays
along with the parameter `shape`, as this makes interfacing with
orginally-in-FORTRAN C libraries through ctypes or cffi possible
(without having to write a C-extension).

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2018-12-30 Thread Laurent Gautier 


Laurent Gautier  added the comment:

Wait. Isn't a `memoryview` memerely a Python object for a buffer inferface, 
whatever its valid attributes or flags might be ?

The perceived oddness that lead to the addition of the keyword 'shape' was a 
good initial instinct that something was off, but this is an incomplete 
workaround .

If the rationale was to follow what `tobytes` is doing, this delegates the 
justification for excluding non 'C' views it. Then I do not understand the 
rationale behind `memoryview.tobytes`'s exclusive relationshop to C-contiguous 
arrays. A memmoryview is a window on a memory region (a Python buffer), and one 
would expect `tobytes` to just return bytes for it (in whatever bytes/strides) 
the memoryview is originally in.

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2018-12-29 Thread Laurent Gautier 


Laurent Gautier  added the comment:

Bump.

What are the next steps here ?

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2018-09-29 Thread Laurent Gautier 


Laurent Gautier  added the comment:

Wouldn't a contiguity argument ('C' or 'F') be simpler ?
 
(Independently, an argument strides is likely also missing from "cast").

Do you know what are the next possible steps here ? Bring this to the 
python-dev list ? Submit a patch ?

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2018-09-28 Thread Laurent Gautier 


Laurent Gautier  added the comment:

@mattip : do you mean that it can currently be achieved by calling `cast` with 
a specific shape parameter ? If the case, how so ?

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[issue34778] Memoryview for column-major (f_contiguous) arrays from bytes impossible to achieve

2018-09-23 Thread Laurent Gautier 


New submission from Laurent Gautier :

The buffer protocol is accounting for the row-major or column-major arrays, and 
that information is shown in the attributes, `c_contiguous` and `f_contiguous` 
respectively, of a memoryview object.

Using the method `cast` allows one to specify a shape but does not allow
to specify whether row or column major:

```
# column-major 3x2 array of bytes that was serialized
b = bytearray([1,2,3,4,5,6])

mv = memoryview(b)
mv_b = mv.cast('b', shape=(3,2))
```

The result object is believed to be row-major and little can be done
to correct it:


```
>>> mv_int.c_contiguous
True
>>> mv_int.c_contiguous = False
AttributeError: attribute 'c_contiguous' of 'memoryview' objects is not writable
```

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components: Interpreter Core
messages: 326167
nosy: lgautier
priority: normal
severity: normal
status: open
title: Memoryview for column-major (f_contiguous) arrays from bytes impossible 
to achieve
type: enhancement
versions: Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8

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[issue18323] 'GzipFile' object has no attribute 'extrastart'

2013-06-28 Thread Laurent Gautier 

New submission from Laurent Gautier:

When creating a `gzip.GzipFile` using the named parameter `fileobj`
rather than filename, iterating over it is broken:
```
AttributeError: 'GzipFile' object has no attribute 'extrastart'
```

The short example below is demonstrating the problem:

## ---

import gzip, tempfile
_data = (b'@WXOVW:25:85', b'ATACGCGGCT'+b'GATCGTAGCG',
 b'+',
 b'@@))BB'+b'???ECCEECC')

data = gzip.zlib.compress(b'\n'.join(_data))
foo = tempfile.NamedTemporaryFile()
foo.write(data)
foo.flush()
foo.seek(0)

gzf = gzip.GzipFile(fileobj=foo)

# this will trigger the AttributeError
for x in gzf:
print(x)

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components: Library (Lib)
messages: 191989
nosy: Laurent.Gautier
priority: normal
severity: normal
status: open
title: 'GzipFile' object has no attribute 'extrastart'
type: crash
versions: Python 2.7

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[issue14398] bz2.BZ2DEcompressor.decompress fail on large files

2012-03-24 Thread Laurent Gautier 

New submission from Laurent Gautier lgaut...@gmail.com:

The call ends with:
Objects/stringobject.c:3884: bad argument to internal function

sys.version:
'2.7.2 (default, Jun 13 2011, 15:14:50) \n[GCC 4.4.5]'
(on 64bit Linux)

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messages: 156698
nosy: Laurent.Gautier
priority: normal
severity: normal
status: open
title: bz2.BZ2DEcompressor.decompress fail on large files
type: crash
versions: Python 2.7

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[issue14398] bz2.BZ2DEcompressor.decompress fail on large files

2012-03-24 Thread Laurent Gautier 

Laurent Gautier lgaut...@gmail.com added the comment:

Wow! Quick follow-up.
 
The data file is about 1.6Gb. Is there a preferred way to pass it on (I suspect 
that the bug tracker is not the preferred way).

The code goes like:

import bz2
f = file(foobar.bz2, mode=rb)
src_buf = f.read()
decomp = bz2.BZ2Decompressor()
tmp = decomp.decompress(src_buf)

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[issue2437] Distutils runtime_library_dirs broken on Windows

2008-05-18 Thread Laurent Gautier 

Laurent Gautier [EMAIL PROTECTED] added the comment:

The bug is still here with Python 2.5.2.

I anyone want to have it work urgently, there is a quick but very ugly
fix: add
g['CC'] = 'gcc' 
into the function _init_nt() in the file Lib\distutils\sysconfig.py
of the Python install.

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