尝试更新MultiSelect小部件时，Bokeh会生成PropertyValueList错误

Question

我正在玩MultiSelect小部件，我发现它产生了一个我无法解释的错误。

以下是没有错误的工作代码：

from bokeh.io import curdoc
from bokeh.layouts import column, widgetbox
from bokeh.models import Slider, Select, TextInput, MultiSelect

df = ["apples", "oranges", "grapes"]

def callback(attr, old, new):
    print(df)
    print("{} changed: Old [ {} ] -> New [ {} ]".format(attr, old, new))
#    multiselect1.update(options = [x for x in df if new in x])


multiselect1 = MultiSelect(title = "multiselect1",
                           name = "multiselect1",
                           value = [],
                           options = df)
multiselect1.on_change('value', callback)

curdoc().add_root(widgetbox(multiselect1))

打印出来的是预期的：

['apples', 'oranges', 'grapes']
value changed: Old [ [] ] -> New [ ['oranges'] ]

关于工作部分......很多 对于 not working part ...只要注释了multiselect1.update(options = [x for x in df if new in x])并且新的callback函数是：

def callback(attr, old, new):
    print(df)
    print("{} changed: Old [ {} ] -> New [ {} ]".format(attr, old, new))
    multiselect1.update(options = [x for x in df if new in x])

...它会生成错误：

['apples', 'oranges', 'grapes']
value changed: Old [ [] ] -> New [ ['oranges'] ]
2018-05-17 13:34:48,755 error handling message Message 'PATCH-DOC' (revision 1): TypeError("'in <string>' requires string as left operand, not PropertyValueList",)

知道为什么会产生这个错误以及如何避免它？

Answer 1

看起来变量new是一个列表，而下面的列表理解需要new是一个字符串：

[x for x in df if new in x]

您可以尝试索引new列表以获取字符串值，如下所示：

[x for x in df if new[0] in x]