如何根据下拉小部件的所选选项更改文本框小部件的描述？（列表字典）答案

【问题标题】：How to change the description of textbox widgets depending on the chosen option of a dropdown widget? (Dictionary of Lists)如何根据下拉小部件的所选选项更改文本框小部件的描述？（列表字典）
【发布时间】：2016-07-12 21:21:19
【问题描述】：

我希望根据下拉小部件的所选选项更改文本框小部件的描述。我想我可以通过使用列表字典来实现这一点。这是我所做的一个例子：

#Lists of text box descriptions
LEF_SOL = ['AMP','DEP','LAGTIME']
INI_SOL = ['AMP','DEP','XWavemaker']
INI_REC = ['Xc','Yc','WID']

# dictionary made with such lists
wave_options = {'left boundary solitary':LEF_SOL, 
            'initial solitary wave':INI_SOL,'rectangular hump':INI_REC}

#dropdown widget of the dictionary
wave_maker = widgets.Dropdown(options=wave_options)

# Textbox 1 description = first object of list depending on the dropdown 
first_option = widgets.BoundedFloatText(width = "20%",height = '50px',
                           description = wave_maker.value[0])

# Textbox 2 description = second object of list depending on the dropdown 
second_option = widgets.BoundedFloatText(width = "20%",height = '50px',
                           description = wave_maker.value[1])

# Textbox 3 description = third object of list depending on the dropdown
third_option = widgets.BoundedFloatText(width = "20%",height = '50px',
                           description = wave_maker.value[2])

display(wave_maker,first_option,second_option,third_option)

然而，当我运行它时，文本框描述仍然是属于出现在下拉列表中的第一个选项的描述。如果下拉列表更改，我希望它们更改。我知道这可以通过“链接”来完成。它应该看起来像这样：

link((wave_maker,'value[0]'), (first_option, 'description'))
link((wave_maker,'value[1]'), (second_option, 'description'))
link((wave_maker,'value[2]'), (third_option, 'description'))

但发生错误：

TypeError: <ipywidgets.widgets.widget_selection.Dropdown
object at   0x7fd47bbbd790> has no trait 'value[0]'

然而，当我将“链接”更改为：

link((wave_maker,'value'), (first_option, 'description'))

然后出现这个错误：

TraitError: The 'description' trait of a BoundedFloatText
instance must be a unicode string, but a value of ['AMP', 'DEP',   'XWavemaker']
 <type 'list'> was specified.

有没有办法解决这个问题？

【问题讨论】：

标签： list dictionary widget ipython jupyter

【解决方案1】：

我发现可以通过使用 traitlets“观察”或“交互”来解决我的问题。我附上了一个“观察”的例子：

wave_options = ('INI_SOL', 'WK_IRR')
int_range = widgets.Dropdown(options=wave_options)
Xc_WK = widgets.BoundedFloatText()
DEP_WK = widgets.BoundedFloatText()

display(int_range,Xc_WK,DEP_WK)

def on_value_change(value):
    if int_range.value == 'WK_IRR':
        Xc_WK.description = 'Xc_WK'
        DEP_WK.description='DEP_WK'

    else:
        Xc_WK.description ='amp'
        DEP_WK.description='DEP'


int_range.observe(on_value_change, 'value')

【讨论】：