Re: [Numpy-discussion] New (old) function proposal.
On Tue, Feb 18, 2014 at 11:27 AM, Sebastian Berg sebast...@sipsolutions.net
wrote:
On Di, 2014-02-18 at 09:05 -0700, Charles R Harris wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut', endvalue=0):
Generate a new array that chops the given array along the given
axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
Just to note, there have been similar proposals with a rolling_window
function. It could be made ND aware, too (though maybe this one is
also).
For example: https://github.com/numpy/numpy/pull/31
Warren
Chuck
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Re: [Numpy-discussion] New (old) function proposal.
yes, but I don't like the name too much. Unfortunately, I can't think of a
better one.
Ben Root
On Tue, Feb 18, 2014 at 11:05 AM, Charles R Harris
charlesr.har...@gmail.com wrote:
Hi All,
There is an old ticket, #1499 https://github.com/numpy/numpy/issues/1499,
that suggest adding a segment_axis function.
def segment_axis(a, length, overlap=0, axis=None, end='cut', endvalue=0):
Generate a new array that chops the given array along the given axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
Chuck
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Re: [Numpy-discussion] New (old) function proposal.
On Di, 2014-02-18 at 09:05 -0700, Charles R Harris wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut', endvalue=0):
Generate a new array that chops the given array along the given axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
Just to note, there have been similar proposals with a rolling_window
function. It could be made ND aware, too (though maybe this one is
also).
Chuck
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Re: [Numpy-discussion] New (old) function proposal.
On 18 Feb 2014 11:05, Charles R Harris charlesr.har...@gmail.com wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut', endvalue=0):
Generate a new array that chops the given array along the given
axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
I'd use it, though haven't looked at the details of this api per set yet.
rolling_window or shingle are better names.
It should probably be documented and implemented to return a view when
possible (using stride tricks). Along with a note that whether this is
possible depends heavily on 32- vs. 64-bitness.
-n
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Re: [Numpy-discussion] New (old) function proposal.
On Tue, Feb 18, 2014 at 9:40 AM, Nathaniel Smith n...@pobox.com wrote:
On 18 Feb 2014 11:05, Charles R Harris charlesr.har...@gmail.com
wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut', endvalue=0):
Generate a new array that chops the given array along the given
axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
I'd use it, though haven't looked at the details of this api per set yet.
rolling_window or shingle are better names.
It should probably be documented and implemented to return a view when
possible (using stride tricks). Along with a note that whether this is
possible depends heavily on 32- vs. 64-bitness.
I believe it does return views when possible. There are two patches
attached to the issue, one for the function and another for tests. So here
is an easy commit for someone ;) The original author seems to be Anne
Archibald, who should be mentioned if this is put in.
Where does 'shingle' come from. I can see the analogy but haven't seen that
as a technical term.
Chuck
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Re: [Numpy-discussion] New (old) function proposal.
On Tue, Feb 18, 2014 at 9:03 AM, Charles R Harris charlesr.har...@gmail.com
wrote:
On Tue, Feb 18, 2014 at 9:40 AM, Nathaniel Smith n...@pobox.com wrote:
On 18 Feb 2014 11:05, Charles R Harris charlesr.har...@gmail.com
wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut',
endvalue=0):
Generate a new array that chops the given array along the given
axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
I'd use it, though haven't looked at the details of this api per set yet.
rolling_window or shingle are better names.
It should probably be documented and implemented to return a view when
possible (using stride tricks). Along with a note that whether this is
possible depends heavily on 32- vs. 64-bitness.
I believe it does return views when possible. There are two patches
attached to the issue, one for the function and another for tests. So here
is an easy commit for someone ;) The original author seems to be Anne
Archibald, who should be mentioned if this is put in.
Where does 'shingle' come from. I can see the analogy but haven't seen
that as a technical term.
In an inkjet printing pipeline, one of the last steps is to split the image
into the several passes that will be needed to physically print it. This is
often done with a tiled, non-overlapping mask, known as a shingling mask.
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Re: [Numpy-discussion] New (old) function proposal.
On 18 Feb 2014 12:04, Charles R Harris charlesr.har...@gmail.com wrote: Where does 'shingle' come from. I can see the analogy but haven't seen that as a technical term. It just seems like a good name :-). -n ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] New (old) function proposal.
On Tue, Feb 18, 2014 at 11:11 AM, Jaime Fernández del Río
jaime.f...@gmail.com wrote:
On Tue, Feb 18, 2014 at 9:03 AM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Tue, Feb 18, 2014 at 9:40 AM, Nathaniel Smith n...@pobox.com wrote:
On 18 Feb 2014 11:05, Charles R Harris charlesr.har...@gmail.com
wrote:
Hi All,
There is an old ticket, #1499, that suggest adding a segment_axis
function.
def segment_axis(a, length, overlap=0, axis=None, end='cut',
endvalue=0):
Generate a new array that chops the given array along the given
axis
into overlapping frames.
Parameters
--
a : array-like
The array to segment
length : int
The length of each frame
overlap : int, optional
The number of array elements by which the frames should overlap
axis : int, optional
The axis to operate on; if None, act on the flattened array
end : {'cut', 'wrap', 'end'}, optional
What to do with the last frame, if the array is not evenly
divisible into pieces.
- 'cut' Simply discard the extra values
- 'wrap' Copy values from the beginning of the array
- 'pad' Pad with a constant value
endvalue : object
The value to use for end='pad'
Examples
segment_axis(arange(10), 4, 2)
array([[0, 1, 2, 3],
[2, 3, 4, 5],
[4, 5, 6, 7],
[6, 7, 8, 9]])
Is there and interest in having this function available?
I'd use it, though haven't looked at the details of this api per set yet.
rolling_window or shingle are better names.
It should probably be documented and implemented to return a view when
possible (using stride tricks). Along with a note that whether this is
possible depends heavily on 32- vs. 64-bitness.
I believe it does return views when possible. There are two patches
attached to the issue, one for the function and another for tests. So here
is an easy commit for someone ;) The original author seems to be Anne
Archibald, who should be mentioned if this is put in.
Where does 'shingle' come from. I can see the analogy but haven't seen
that as a technical term.
In an inkjet printing pipeline, one of the last steps is to split the
image into the several passes that will be needed to physically print it.
This is often done with a tiled, non-overlapping mask, known as a
shingling mask.
Just for reference, scikit-image has a similar function (w/o padding)
called `view_as_blocks`:
http://scikit-image.org/docs/0.9.x/api/skimage.util.html#view-as-blocks
(and a rolling-window version called `view_as_windows`).
Cheers,
-Tony
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