Streaming image data row-by-row?

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1

Hi all,
I’d like to use ‘ColumnDataSource.stream’ for an image which size grows row-by-row.

I gave it a try (using a numpy array) but the appended data does seem to be properly interpreted.

Is ‘ColumnDataSource.stream’ supposed to work for image?

Thanks,

N.

2

Hi,

The streaming API lets you stream data to the end of a *column*. In the case of images, the columns contain 2d arrays as elements, so the stream API would only let you stream a new image, to the end of a column of images. If you want to stream "inside" one to of the existing images, you will need to do something more sophisticated. It's possible (though I have not tried) that the .patch API might be useful for "reaching in" to a single image. Alternatively, the spectrogram streams single columns into a larger image with the use of a custom extension:

  https://github.com/bokeh/bokeh/tree/master/examples/app/spectrogram

Thanks,

Bryan

···

On Feb 13, 2017, at 15:59, nicolas.fr <[email protected]> wrote:

Hi all,
I'd like to use 'ColumnDataSource.stream' for an image which size grows row-by-row.
I gave it a try (using a numpy array) but the appended data does seem to be properly interpreted.
Is 'ColumnDataSource.stream' supposed to work for image?
Thanks,
N.

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1 Like
3

The .patch API sounds interesting but I’m afraid that its indexing principle is not compatible with images. The documentation says:

This method should be passed a dictionary that maps column names to lists of tuples, each of the form (index, new_value). The value at the given index for that column will be updated with the new value.

``

As far as, we have an image at each index of the column, I don’t see how I can reach a specific row in the image using a scalar index.

Anyway, I will have a look to the spectrogram example but it looks quite advanced (seems to make use of a some specific JS code).

···

Le lundi 13 février 2017 23:40:18 UTC+1, Bryan Van de ven a écrit :

Hi,

The streaming API lets you stream data to the end of a column. In the case of images, the columns contain 2d arrays as elements, so the stream API would only let you stream a new image, to the end of a column of images. If you want to stream “inside” one to of the existing images, you will need to do something more sophisticated. It’s possible (though I have not tried) that the .patch API might be useful for “reaching in” to a single image. Alternatively, the spectrogram streams single columns into a larger image with the use of a custom extension:

    [https://github.com/bokeh/bokeh/tree/master/examples/app/spectrogram](https://github.com/bokeh/bokeh/tree/master/examples/app/spectrogram)

Thanks,

Bryan

On Feb 13, 2017, at 15:59, nicolas.fr [email protected] wrote:

Hi all,

I’d like to use ‘ColumnDataSource.stream’ for an image which size grows row-by-row.

I gave it a try (using a numpy array) but the appended data does seem to be properly interpreted.
Is ‘ColumnDataSource.stream’ supposed to work for image?

Thanks,

N.

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For more options, visit https://groups.google.com/a/continuum.io/d/optout.