Python 具有多个IPyWidget下拉列表的交互式Covid图

我正在尝试组装一个Jupyter笔记本，允许用户在下拉列表中输入一个州，这将在第二个下拉列表中改变结果，只显示该州的城市。一旦选择了城市，就可以按下按钮刷新图表（我知道你可以使用手动交互，但无法正常运行），并显示结果数据（一段时间后的新冠病例）。我已经成功地制作了一些小部件，但是我无法正确地绘制数据

这是我第一次在Jupyter中使用小部件，我对交互、交互性、显示和观察（更不用说不推荐的on_trait_更改）有点迷茫。这是我到目前为止所拥有的

from ipywidgets import interact, widgets
from bqplot import pyplot as plt
import pandas as pd

#make example DF
date_list = ['2020-02-01','2020-02-01','2020-02-01','2020-02-01','2020-02-02','2020-02-02','2020-02-02','2020-02-02']
state_list = ['CA','NY','CA','NY','CA','NY','CA','NY']
city_list = ['San Fran','NYC','LA','Albany','San Fran','NYC','LA','Albany']
cases_list = [0,0,0,0,2,6,4,8]

df = pd.DataFrame(index=date_list)
df['state'] = state_list
df['city'] = city_list
df['cases'] = cases_list

#getting unique state and city list sorted in alphabetical order
state_unique = df['state'].unique()
state_unique.sort()

state = widgets.Dropdown(
    options=['All'] + list(state_unique),
    value='CA', #indicates default starting value
    description='State:', #this is the label for the dropdown
)

city = widgets.Dropdown(
    description='City:',
)


# function that updates 'city' dropdown depending on value in 'state' dropdown
def list_cities(x):
    if state.value == 'All':
        city.options = ['']
        return city_list
    else:
        temp = ['All'] + sorted(df.loc[df['state'].eq(state.value),'city'].unique())
        city.options = temp

state.observe(list_cities, names = 'value') #the names part tells the observe the change name to look for, this is only looking for value changes



b_refresh = widgets.Button(
    description='Refresh',
    icon='fa-refresh',
    button_style='warning',
    layout=widgets.Layout(width='100px')
)

# plotting function
def set_plot(x_data,y_data):
    plt.plot(x_data, y_data)
    plt.show()

x = list(df.index.unique())
y = df.loc[\
    (df['city']==city.value)&\
    (df['state']==state.value),'cases']

b_refresh.on_click(set_plot(x, y))

display (state,city,b_refresh)

---

不清楚你在问什么。我建议您找到一个示例工作小部件实现，它看起来像您想要的，然后逐步修改它以将其更改为您想要的。谢谢Aaron！我想我已经弄明白了，然后把代码发出去了。我需要有一个单一的问题，每个职位的工作。

from ipywidgets.widgets import Dropdown, Button
from ipywidgets.widgets import Layout, HBox, VBox
import bqplot as bq
import pandas as pd

#make example DF
date_list = ['2020-02-01','2020-02-01','2020-02-01','2020-02-01','2020-02-07','2020-02-07','2020-02-07','2020-02-07']
state_list = ['CA','NY','CA','NY','CA','NY','CA','NY']
city_list = ['San Fran','NYC','LA','Albany','San Fran','NYC','LA','Albany']
cases_list = [0,10,0,12,2,6,4,8]

df = pd.DataFrame(index=date_list)
df['state'] = state_list
df['city'] = city_list
df['cases'] = cases_list

df.index = pd.to_datetime(df.index)
df.rename_axis("date", axis='index', inplace=True)

#getting unique state list sorted in alphabetical order
state_unique = df['state'].unique()
state_unique.sort()

#make graphical parts - 2 dropdowns and refresh button
state = Dropdown(
    options=['All'] + list(state_unique),
    value='All', #indicates default starting value
    description='State:', #this is the label for the dropdown
    layout=Layout(width='200px',
    margin = '0px 0px 0px 0px')
)

city = Dropdown(
    description='City:',
    layout=Layout(width='200px',
    margin = '0px 0px 0px 0px')
)

b_refresh = Button(
    description='Refresh',
    icon='fa-refresh',
    button_style='warning',
    layout=Layout(width='100px',
              margin = '0px 0px 0px 60px')
)

#make graph parts
x = list(df.index.unique())
y = list(df.groupby('date')['cases'].sum())

xs = bq.DateScale()
ys = bq.LinearScale(min=0)

line = bq.Lines(
    x=x, 
    y=y, 
    scales={'x': xs, 'y': ys}
    )

x_ax = bq.Axis(
    scale=xs, 
    label='Dates', 
    grid_lines='solid', 
    tick_format='%m-%d', 
    tick_rotate=-0, 
    label_location ='middle',
    label_offset = "40px"
)

y_ax = bq.Axis(
    scale=ys, 
    orientation='vertical', 
    tick_format=',d', 
    label='FillInLater', 
    grid_lines='solid',
    label_offset = "60px"
)

# function that updates 'city' dropdown depending on value in 'state' dropdown
def list_cities(x):
    if state.value == 'All':
        global y
        city.options = ['']
        y = list(df.groupby('date')['cases'].sum())
    else:
        temp = ['All'] + sorted(df.loc[df['state'].eq(state.value),'city'].unique())
        city.options = temp
        update_city(x)


# function that updates graph's y values depending on value in 'city' dropdown
def update_city(x):
    global y
    if city.value == 'All':
        matching_cities = df.loc[(df['state']==state.value),'cases'].to_frame(name='cases')
        y = list(matching_cities.groupby('date')['cases'].sum())       
    else:
        y = list(df.loc[\
        (df['city']==city.value)&\
        (df['state']==state.value),'cases'])

# update plot function
def set_plot(b):
    global y
    line.y = [y]


#assign widget actions to functions
state.observe(list_cities, names = 'value') #the names part tells .observe the change name to look for, this is only looking for value changes
city.observe(update_city, names = 'value')        
b_refresh.on_click(set_plot)

#display all
fig = bq.Figure(
    layout=Layout(width='95%', height='400px', border ='solid 1px gray'),
    axes=[x_ax, y_ax],
    marks=[line],
    fig_margin=dict(top=10, bottom=80, left=80, right=20),
    animation_duration=500
)

box = HBox(
    children=(state, city, b_refresh),
    layout=Layout(margin = '10px 0px 10px 0px')
)

vert_box  = VBox(
    children=(box, fig),
    layout=Layout(border='solid 1px gray', margin = '0 0 0 0')
)

display (vert_box)