Jupyter notebook 上的多个依赖小部件（下拉菜单）

Question

我正在关注如何从这里处理 jupyter 笔记本上的多个依赖小部件的示例：

Dynamically changing dropdowns in IPython notebook widgets and Spyre

在该示例中，代码解决方案如下：

from IPython.html import widgets
from IPython.display import display

geo={'USA':['CHI','NYC'],'Russia':['MOW','LED']}

def print_city(city):
    print city

def select_city(country):
    cityW.options = geo[country]


scW = widgets.Dropdown(options=geo.keys())
init = scW.value
cityW = widgets.Dropdown(options=geo[init])
j = widgets.interactive(print_city, city=cityW)
i = widgets.interactive(select_city, country=scW)
display(i)
display(j)

所以，第二个下拉菜单取决于第一个下拉菜单的值。 这里的问题是：如果我想创建依赖于第二个下拉列表的第三个下拉列表怎么办？假设上面的每个城市（CHI、NYC、MOW、LED）都有一些区，我想要第三个下拉菜单，每次更新城市时都会改变。

希望问题清楚，谢谢！

Answer 1

以防万一您从未找到解决方案：我这里有一个适用于 python 3 的解决方案。我已经评论了我从原始代码中更改的所有内容。希望对你有帮助！

from IPython.html import widgets
from IPython.display import display

geo={'USA':['CHI','NYC'],'Russia':['MOW','LED']}

geo2={'CHI':['1','2'],'NYC':['3','4'],'MOW':['5','6'],'LED':['7','8']} #create dictionary with city districts

def print_city(city,district):
    print(city)
    print(district) #add in command to print district

def select_city(country):
    cityW.options = geo[country]

#add in 'select district' function that looks in the new dictionary
def select_district(city):
    districtW.options = geo2[city]

scW = widgets.Dropdown(options=geo.keys())
init = scW.value
cityW = widgets.Dropdown(options=geo[init])


init2= cityW.value #new start value for district dropdown
districtW = widgets.Dropdown(options=geo2[init2]) #define district dropdown widget

j = widgets.interactive(print_city, city=cityW, district=districtW) #define district value
i = widgets.interactive(select_city, country=scW)

k = widgets.interactive(select_district, city=cityW) #call everything together with new interactive

display(i)
display(j)

Answer 2

使用interactive 对我来说有点笨拙。我已经为原始页面here 中的两个依赖小部件提供了更清晰和简洁的答案。下面我为多个依赖的小部件提供我的答案。

from ipywidgets import interact, Dropdown

geo = {'USA':['CHI','NYC'],'Russia':['MOW','LED']}
geo2={'CHI':['1','2'],'NYC':['3','4'],'MOW':['5','6'],'LED':['7','8']}

countryW = Dropdown(options = geo.keys())
cityW = Dropdown(options = geo[countryW.value]) # options = geo[countryW.value] is to remove inital error but not that necessary.
districtW = Dropdown()

@interact(country = countryW, city = cityW, district = districtW)
def print_city(country, city, district):
    cityW.options = geo[country] # Here is the trick, i.e. update cityW.options based on country, namely countryW.value.
    districtW.options = geo2[city] # Dittoo
    print(country, city, district)

另一种方法是使用如下所示的显式更新函数。请记住，更新速度可能不会那么快。代码运行良好。

from ipywidgets import interact, Dropdown

geo = {'USA':['CHI','NYC'],'Russia':['MOW','LED']}
geo2={'CHI':['1','2'],'NYC':['3','4'],'MOW':['5','6'],'LED':['7','8']}

countryW = Dropdown(options = geo.keys())
cityW = Dropdown()
districtW = Dropdown()

def update_cityW_options(*args): # *args represent zero (case here) or more arguments.
    cityW.options = geo[countryW.value]
cityW.observe(update_cityW_options) # Here is the trick, i.e. update cityW.options based on countryW.value.

def update_districtW_options(*args):
    districtW.options = geo2[cityW.value]
districtW.observe(update_districtW_options)

@interact(country = countryW, city = cityW, district = districtW)
def print_city(country, city, district):
    print(country, city, district)