Bokeh ColumnDataSource Error when identifying as source - why?

I'm getting error messages when identifying ColumnDataSource as my source, want to do it right.

Let me show the errors.

First, I generate some random data in a DataFrame and put it into the ColumnDataSource:

col_list = ['ob1','ob2','ob3','ob4','ob5']
df = pd.DataFrame(np.random.uniform(73.965,74.03,size=(25, 5)).astype(float), columns=col_list)
df.reset_index(inplace=True)
df = df.rename(columns = {'index':'order'})
df['order'] = df['order'] + 1

cds = ColumnDataSource(data=df)

So far so good.

I try to generate a graph:

p = figure(title = 'ColumnDataSource test', sizing_mode = 'stretch_both')
p.line(x=cds.data['order'], y = cds.data['ob1'], source = cds.data[['order', 'ob1']])
show(p)

and get the following error:

Traceback (most recent call last):
  File "e:\Black_Belt_Six_Sigma\first_take.py", line 57, in <module>
    p.line(x=cds.data['order'], y = cds.data['ob1'], source = cds.data[['order', 'ob1']])
TypeError: unhashable type: 'list'

Fair enough, I won't give the source parameter a list and try again:

p = figure(title = 'ColumnDataSource test', sizing_mode = 'stretch_both')
p.line(x=cds.data['order'], y = cds.data['ob1'], source = cds.data)
show(p)

I get no graph but only the following error:

RuntimeError:

Expected x and y to reference fields in the supplied data source.

When a 'source' argument is passed to a glyph method, values that are sequences
(like lists or arrays) must come from references to data columns in the source.

For instance, as an example:

    source = ColumnDataSource(data=dict(x=a_list, y=an_array))

    p.circle(x='x', y='y', source=source, ...) # pass column names and a source

Alternatively, *all* data sequences may be provided as literals as long as a
source is *not* provided:

    p.circle(x=a_list, y=an_array, ...)  # pass actual sequences and no source

Based on this error message I've tried the following:

cds = ColumnDataSource(data=dict(order = df['order'].to_list(), ob1 = df['ob1'].to_list()))

p = figure(title = 'ColumnDataSource test', sizing_mode = 'stretch_both')
p.line(x=cds.data['order'], y = cds.data['ob1'], source = cds)
show(p)

And

cds = ColumnDataSource(data=dict(order = df['order'], ob1 = df['ob1']))

p = figure(title = 'ColumnDataSource test', sizing_mode = 'stretch_both')
p.line(x=cds.data['order'], y = cds.data['ob1'], source = cds)
show(p)

Both keep returning the same error message.

I can get a graph/plot if I don't specify the source parameter, so maybe that's the right course of action? Seems odd, I imagine it's important if the developers made it a parameter.

Solution

You should pass your dictionary keys order and ob1 directly to the arguments x and y. And your ColumDataSource cds to the argument source (see more examples here):

import pandas as pd
import numpy as np
from bokeh.plotting import figure, show
from bokeh.models import ColumnDataSource


col_list = ['ob1','ob2','ob3','ob4','ob5']
df = pd.DataFrame(np.random.uniform(73.965,74.03,size=(25, 5)).astype(float), columns=col_list)
df.reset_index(inplace=True)
df = df.rename(columns = {'index':'order'})
df['order'] = df['order'] + 1

cds = ColumnDataSource(data=df)

p = figure(title = 'ColumnDataSource test', sizing_mode = 'stretch_both')
p.line(x='order',y='ob1',source=cds)
show(p)