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Running
on
Zero
Running
on
Zero
| from __future__ import annotations | |
| from toolz import identity | |
| from . import transfer_functions as tf | |
| from . import reductions | |
| from . import core | |
| class Pipeline: | |
| """A datashading pipeline callback. | |
| Given a declarative specification, creates a callable with the following | |
| signature: | |
| ``callback(x_range, y_range, width, height)`` | |
| where ``x_range`` and ``y_range`` form the bounding box on the viewport, | |
| and ``width`` and ``height`` specify the output image dimensions. | |
| Parameters | |
| ---------- | |
| df : pandas.DataFrame, dask.DataFrame | |
| glyph : Glyph | |
| The glyph to bin by. | |
| agg : Reduction, optional | |
| The reduction to compute per-pixel. Default is ``count()``. | |
| transform_fn : callable, optional | |
| A callable that takes the computed aggregate as an argument, and | |
| returns another aggregate. This can be used to do preprocessing before | |
| passing to the ``color_fn`` function. | |
| color_fn : callable, optional | |
| A callable that takes the output of ``tranform_fn``, and returns an | |
| ``Image`` object. Default is ``shade``. | |
| spread_fn : callable, optional | |
| A callable that takes the output of ``color_fn``, and returns another | |
| ``Image`` object. Default is ``dynspread``. | |
| height_scale: float, optional | |
| Factor by which to scale the provided height | |
| width_scale: float, optional | |
| Factor by which to scale the provided width | |
| """ | |
| def __init__(self, df, glyph, agg=reductions.count(), | |
| transform_fn=identity, color_fn=tf.shade, spread_fn=tf.dynspread, | |
| width_scale=1.0, height_scale=1.0): | |
| self.df = df | |
| self.glyph = glyph | |
| self.agg = agg | |
| self.transform_fn = transform_fn | |
| self.color_fn = color_fn | |
| self.spread_fn = spread_fn | |
| self.width_scale = width_scale | |
| self.height_scale = height_scale | |
| def __call__(self, x_range=None, y_range=None, width=600, height=600): | |
| """Compute an image from the specified pipeline. | |
| Parameters | |
| ---------- | |
| x_range, y_range : tuple, optional | |
| The bounding box on the viewport, specified as tuples of | |
| ``(min, max)`` | |
| width, height : int, optional | |
| The shape of the image | |
| """ | |
| canvas = core.Canvas(plot_width=int(width*self.width_scale), | |
| plot_height=int(height*self.height_scale), | |
| x_range=x_range, y_range=y_range) | |
| bins = core.bypixel(self.df, canvas, self.glyph, self.agg, | |
| antialias=self.glyph.antialiased) | |
| img = self.color_fn(self.transform_fn(bins)) | |
| return self.spread_fn(img) | |