Question

我想在Bokeh中结合这两个例子：

http://bokeh.pydata.org/en/latest/docs/gallery/image.html http://bokeh.pydata.org/en/latest/docs/user_guide/interaction/callbacks.html#customjs-for-widgets

这个想法似乎很简单。我想绘制第一个链接中显示的图像，然后使用交互式滑块改变正弦函数的频率：

import numpy as np

from bokeh.plotting import figure, show, output_file
from bokeh.models import CustomJS, ColumnDataSource, Slider
from bokeh.io import vform


N = 10

x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx)*np.cos(yy)  

output_file("image.html", title="image.py example")

source = ColumnDataSource(data={'d': d, 'x': x, 'y': y})

p = figure(x_range=[0, 10], y_range=[0, 10])
p.image([source.data['d']], x=[0], y=[0], dw=[10], dh=[10], palette="Spectral11")

callback = CustomJS(args=dict(source=source), code="""
        var data = source.get('data');
        var f = cb_obj.get('value')
        x = data['x']
        y = data['y']
        d = data['d']
        for (i = 0; i < x.length; i++) {
            for (i = 0; i < x.length; i++){
                d[i][j] = Math.sin(f*x[i])*Math.cos(y[j])
        }
        source.trigger('change');
    """)

slider = Slider(start=0.1, end=4, value=1, step=.1, title="angular frequency", callback=callback)

layout = vform(slider, p)

show(layout)

图表绘制正确，但图像永远不会更新。问题几乎肯定存在于我如何绘制图像：

p.image([source.data['d']], x=[0], y=[0], dw=[10], dh=[10], palette="Spectral11")

我认为这不是你如何正确地将绘图附加到源对象。我只是传入一个数组，这解释了为什么当源更改时图不会更新，但我不确定图像函数的正确方法是什么。如果我将语句更改为：

p.image(['d'], x=[0], y=[0], dw=[10], dh=[10], source=source, palette="Spectral11")

它无法正确绘制。我不确定这只是语法问题还是更深层次的问题。任何指针将不胜感激。提前致谢。

Answer 1

我正在处理类似问题几天。最后我做到了。首先，注意ColumnDataSource函数中的方括号[]。数据允许多个图像。因此，在回调函数中，您应该使用[0]来获取一个图像的数据。在图像的源中使用'x'和'y'与图像x = [0]和y [0]的位置冲突，所以我使用了xx和yy。我想提一下，我从tobyhodges color_sliders.py的示例中借用了代码：一种将滑块信息推送到已经定义的回调函数的方法。代码如下：

import numpy as np
from bokeh.plotting import figure, show, output_file
from bokeh.models import CustomJS, ColumnDataSource, Slider
from bokeh.io import vform

N = 100

x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx)*np.cos(yy)  

output_file("image.html", title="image.py example")

source = ColumnDataSource(data={'d': [d], 'xx': [x], 'yy': [y]})

p = figure(x_range=[0, 10], y_range=[0, 10])
p.image(image="d", x=[0], y=[0], dw=[10], dh=[10], palette="Spectral11",source=source)

callback = CustomJS(args=dict(source=source), code="""
        var xx = source.get('data')['xx'][0];
        var yy = source.get('data')['yy'][0];
        var d = source.get('data')['d'][0];
        var f = slider.get('value');
        for (var i = 0; i < xx.length; i++) {
            for (var j = 0; j < yy.length; j++){
                d[i][j] = Math.sin(f * xx[i]) * Math.cos(yy[j]);
            }
        }
        source.trigger('change');
    """)

slider = Slider(start=0.1, end=4, value=1, step=.1, title="angular frequency", callback=callback)
callback.args['slider'] = slider
layout = vform(slider, p)
show(layout)

为了避免最新版本的bokeh（我刚安装的版本是0.12.3）中的弃用警告，我修改了以下代码。在此代码中，我不使用数据源作为图像。在CustomJS内，我传递了图片句柄“im”，并将数据源设为im.data_source。

import numpy as np
import bokeh
import bokeh.plotting

N = 100

x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx)*np.cos(yy)  

source = bokeh.models.ColumnDataSource(data={'x': [x], 'y': [y]})

p = bokeh.plotting.figure(x_range=[0, 10], y_range=[0, 10])
im = p.image(image=[d], x=[0], y=[0], dw=[10], dh=[10], palette="Spectral11")

callback = bokeh.models.CustomJS(args=dict(source=source,im=im), code="""
        var x = source.data['x'][0];
        var y = source.data['y'][0];
        var image_source = im.data_source;
        var d = image_source.data['image'][0];
        var f = slider.value;
        for (var i = 0; i < x.length; i++) {
            for (var j = 0; j < y.length; j++){
                d[i][j] = Math.sin(f * x[i]) * Math.cos(f * y[j]);
            }
        }
        image_source.trigger('change');
    """)

slider = bokeh.models.Slider(start=0.1, end=4, value=1, step=.1, 
                             title="angular frequency", callback=callback)
callback.args['slider'] = slider
layout = bokeh.models.layouts.Column(slider, p)

bokeh.io.output_file("image.html", title="image.py example")
bokeh.io.save(layout)

散景版0.12.4的更新：

更改：现在输出的是Jupyter笔记本。要获取html页面，只需按照以前的版本。此散景版本中的新功能：JavaScript上的数组现在是一维数组。

import numpy as np
import bokeh
import bokeh.plotting

N = 100

x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx)*np.cos(yy)  

source = bokeh.models.ColumnDataSource(data={'x': [x], 'y': [y]})

p = bokeh.plotting.figure(plot_width=300, plot_height=300,x_range=[0, 10], y_range=[0, 10])
im = p.image(image=[d], x=[0], y=[0], dw=[10], dh=[10], palette="Spectral11")

callback = bokeh.models.CustomJS(args=dict(source=source,im=im), code="""
        var x = source.data['x'][0];
        var y = source.data['y'][0];
        var image_source = im.data_source;
        var d = image_source.data['image'][0];
        var f = slider.value;
        for (var j = 0; j < y.length; j++){
            for (var i = 0; i < x.length; i++) {
                d[j*y.length + i] = Math.sin(f * x[i]) * Math.cos(f * y[j]);
            }
        }
        image_source.trigger('change');
    """)

slider = bokeh.models.Slider(start=0.1, end=4, value=1, step=.1,
                             title="angular frequency",callback=callback)
callback.args['slider'] = slider
layout = bokeh.models.layouts.Row(p,slider)

bokeh.io.output_notebook()
bokeh.io.show(layout)

散景版0.12.15的更新：

import numpy as np
import bokeh
import bokeh.plotting

N = 100

x = np.linspace(0, 10, N)
y = np.linspace(0, 10, N)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx)*np.cos(yy)  

source = bokeh.models.ColumnDataSource(
    data=dict(values=[d],x_vals=[x],y_vals=[y]))

p = bokeh.plotting.figure(plot_width=300, plot_height=300,
    x_range=[0, 10], y_range=[0, 10])
p.image(image='values', x=0, y=0, dw=10, dh=10, 
    palette="Spectral11", source=source)

callback = bokeh.models.CustomJS(args=dict(source=source), code="""
    var f = slider.value;
    var x = source.data['x_vals'][0];
    var y = source.data['y_vals'][0];
    var d = source.data['values'][0];
    for (var j = 0; j < y.length; j++){
        for (var i = 0; i < x.length; i++) {
            d[j*y.length + i] = Math.sin(f*x[i]) * Math.cos(f*y[j]);
        }
    }
    source.change.emit();
    """)

slider = bokeh.models.Slider(start=0.1, end=4, value=1, step=.1,
    title="angular frequency",callback=callback)
callback.args['slider'] = slider
layout = bokeh.models.layouts.Row(p,slider)

bokeh.io.output_notebook()
bokeh.io.show(layout)

散景：在图像绘图中实现自定义JavaScript

1 个答案: