# Why is this legend going into party mode rotating across colors when using a slider with a callback?

**URL:** <https://discourse.bokeh.org/t/why-is-this-legend-going-into-party-mode-rotating-across-colors-when-using-a-slider-with-a-callback/4544>\
**Category:** Community Support\
**Created:** [January 18, 2020, 2:47am UTC](https://discourse.bokeh.org/t/why-is-this-legend-going-into-party-mode-rotating-across-colors-when-using-a-slider-with-a-callback/4544 "2020-01-18T02:47:38Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![carolyn](https://discourse.bokeh.org/user_avatar/discourse.bokeh.org/carolyn/32/1316_2.png) [@carolyn](https://discourse.bokeh.org/u/carolyn)\
**Post date:** [January 23, 2020, 6:34pm UTC](https://discourse.bokeh.org/t/why-is-this-legend-going-into-party-mode-rotating-across-colors-when-using-a-slider-with-a-callback/4544/4 "2020-01-23T18:34:16Z")

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Here’s an example. You’re right in that we’re basically replicating the functionality of a CDSView without using that class, since it’s the class that seems to be causing the legend issues.

```
from bokeh.io import show
from bokeh.models import Slider, CustomJS, ColumnDataSource
from bokeh.plotting import figure
from bokeh.layouts import column

master_cds = ColumnDataSource(data=dict(
    x=[1, 2, 3, 4, 5, 6, 7, 8, 9],
    y=[3, 2, 1, 3, 2, 1, 3, 2, 1],
    color=['red', 'red', 'red', 'green', 'green', 'green', 'blue', 'blue', 'blue'],
    group=['A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C']
))

subset_cds = ColumnDataSource(data=master_cds.data.copy())

min_x_slider = Slider(start=0, value=0, end=10, step=1)
new_callback = CustomJS(args=dict(master_cds=master_cds, subset_cds = subset_cds, min_x_slider=min_x_slider), code="""
    // clear out subset CDS to be rebuilt
    subset_cds.clear();
    
    // create a subset CDS by pulling out only the x-values >= our set minimum.
    // iterate over the contents of the 'x' array and check for value. 
    for (i = 0; i < master_cds.data.x.length; i++) { 
      if (master_cds.data.x[i] > min_x_slider.value) {
        subset_cds.data.x.push(master_cds.data.x[i]);
        subset_cds.data.y.push(master_cds.data.y[i]);
        subset_cds.data.color.push(master_cds.data.color[i]);
        subset_cds.data.group.push(master_cds.data.group[i]);
      }
    };      
    subset_cds.change.emit();
    """
    )
min_x_slider.js_on_change('value', new_callback)

p = figure(x_range=(0, 10), y_range=(-1, 5), plot_height=300, tools='save')

p.circle(x='x', y='y', radius=0.5, color='color', legend_field='group', source=subset_cds)

col = column([p, min_x_slider])
show(col)
```

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_[View the full topic](https://discourse.bokeh.org/t/why-is-this-legend-going-into-party-mode-rotating-across-colors-when-using-a-slider-with-a-callback/4544)._