使用ipywidgets按钮返回DataFrame

Question

我目前正在创建一个继承了pandas的DataFrame的类。我感兴趣的是开发一个名为'new_filter‘的方法，它是DataFrame命令的一种更花哨的执行方式：

import pandas as pd
from ipywidgets import widgets
from IPython.display import display
import numpy as np

class Result(pd.DataFrame):

@property
def _constructor(self):
    return Result

def _filter_done(self, c):
    self._column_name = self._filter_dd.value
    self._expression = self._filter_txt.value
    return self[eval('self.'+ self._column_name +'  '+self._expression)]

def new_filter(self):
    self._filter_dd = widgets.Dropdown(options=list(self.columns),
                                            description='Column:')
    self._filter_txt = widgets.Text(description='Expr:')
    self._filter_button = widgets.Button(description = 'Done')
    self._filter_box = widgets.VBox([self._filter_dd, self._filter_txt, self._filter_button])
    display(self._filter_box)
    self._filter_button.on_click(self._filter_done)

创建如下对象后：

test = Result(np.random.randn(3,4), columns=['A','B','C','D']) #just an example
test_2 = test.new_filter()

然后，例如：Widget Output

我想要的是'test_2‘是来自'Result’类的对象。对此有什么解决方案吗？

Answer 1

首先，您必须在函数new_filter中返回一些内容。其次，如果你想要修改相同的对象，我认为这有点难。您可以做的一件事是拥有一个具有可在_filter_done中更新的特征的对象。

下面是一个小例子，告诉你如何做到这一点：

import pandas as pd
from ipywidgets import widgets
from IPython.display import display
import numpy as np

class Result(pd.DataFrame):
    @property
    def _constructor(self):
        return Result

    def _filter_done(self, obj, c):
        ## obj is the obejct to be modified. 
        ## Updating its data attribute to have the filtered data.
        self._column_name = self._filter_dd.value
        self._expression = self._filter_txt.value
        obj.data = self[eval('self.'+ self._column_name +'  '+self._expression)]

    def new_filter(self):
        self._filter_dd = widgets.Dropdown(options=list(self.columns),
                                            description='Column:')
        self._filter_txt = widgets.Text(description='Expr:')
        self._filter_button = widgets.Button(description = 'Done')
        self._filter_box = widgets.VBox([self._filter_dd, self._filter_txt, self._filter_button])
        display(self._filter_box)

        result_obj = FilterResult()
        self._filter_button.on_click(lambda arg: self._filter_done(result_obj, arg))
        return result_obj

from traitlets import HasTraits
from traittypes import DataFrame

class FilterResult(HasTraits):
    data = DataFrame()

使用与问题中相同的示例代码，即，

test = Result(np.random.randn(3,4), columns=['A', 'B', 'C','D']) #just an example
test_2 = test.new_filter()

您可以看到，无论何时单击done，更新后的dataframe都在test_2.data中。