使用 Bokeh Slider 滑动图像

2022-01-24 00:00:00 python bokeh interactive slider javascript

我正在尝试借助滑块无缝地传达大量科学数据.

I am trying to convey a large amount of scientific data seamlessly with the help of sliders.

我从 Bokeh 开始，对 JavaScript 几乎一无所知.我尝试设置第一种方法来滑过两个图像，但我无法刷新图像.

I am beginning with Bokeh and have close to no knowledge in javascript. I tried to setup a first approach to be able to slide through two images, but I cannot get the image to refresh.

假设我的文件夹中有 1.png 和 2.png.

Suppose I have 1.png and 2.png in my folder.

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

output_file('image.html')

source = ColumnDataSource(data=dict(url=['1.png']))

p = Figure(x_range=(0,1), y_range=(0,1))

callbackimg = CustomJS(args=dict(source=source), code="""
    var data = source.get('data');
    var f = cb_obj.get('value')
    old = data['url'][0]
    data['url'][0]= old.replace("1","f")
    source.trigger('change');
""")

p.image_url('url',source=source, x=0, y=1,w=1,h=1)
slider = Slider(start=1, end=2, value=1, step=1, title="image number",     callback=callbackimg)

layout = vform(slider, p)
show(layout)

我改编了 Bokeh Widget Doc 用于滑块和处理散景图像.

I adapted examples from Bokeh Widget Doc for the slider and working with images in bokeh.

我的想法是滑块，通过 callbackimg 片段，将修改包含 url 的源，即要加载的图像的名称.我认为，现在，对源中的字符串的简单访问，并通过滑块的当前值进行替换(因此当滑块从 1 变为 2 时，它应该从 1.png 跳到 2.png)应该做这个伎俩.

My idea is that the slider, through the callbackimg snippet, will modify the source which contains the url, i.e the name of the image to load. I thought, for now, that a simple access to the string in the source, and a replacement through the current value of the slider (so it should jump from 1.png to 2.png as the slider goes from 1 to 2) should do the trick.

然而，一切都没有改变.我怀疑我在 Javascript 代码段中做错了什么.

However, nothing is changing. I suspect I am doing something wrong in the Javascript snippet.

感谢您的反馈

我根据@bigreddot 的建议编辑了代码，但现在滑块在2"位置滑动时只显示一个空图.在我的回答中解决了这个问题

I edited the code according to the suggestions of @bigreddot, but now the slider shows simply an empty figure when sliding in position '2'. Solved the issue, in my answer below

推荐答案

问题是这样的:

url = data['url'][0]
url.replace("1","f")

replace 方法返回一个 new 字符串(您会立即将其丢弃)，因此您实际上并未更改列数据源中的任何内容.你需要这样的东西:

The replace method returns a new string (which you immediately discard), so you are not actually changing anything in the column data source. You need something like:

old = data['url'][0]
data['url'] = old.replace("1","f")

相关文章