过滤器,替换python plot中的组值

原始数据帧

             Country  Gender  Arr-Dep  Year  Value
0            Austria    Male  IN  1974  13728
1            Austria    Male  OUT  1974  17977
2            Austria  Female  IN  1974   8541
3            Austria  Female  OUT  1974   8450
4            Austria   Total  IN  1974  22269
5            Austria   Total  OUT  1974  26427
6            Belgium    Male  IN  1974   2412
7            Belgium    Male  OUT  1974   2800
8            Belgium  Female  IN  1974   2105
9            Belgium  Female  OUT  1974   2100
10           Belgium   Total  IN  1974   4517

作为开始 在我的代码中,我使用了以下库(在带有脱机绘图的Jupyter笔记本中):

import pandas as pd
import numpy as np
import plotly as py
import plotly.figure_factory as ff
import plotly.graph_objs as go
from IPython import display
import os
py.offline.init_notebook_mode()

那么

#Replace non numerical values from the Value column
df1['Value'] = df1['Value'].replace('-', np.nan)

#Groupby Country
df1 = df1.groupby(['Year'], as_index=False)['Value'].sum()

那么 ,我使用绘图创建图形:

#Plot everything in a graph
py.offline.iplot({
    "data": [go.Line(x=df1.Year,
            y=df1.Value)],
    "layout": go.Layout(title="Immigration through the years")
}) 

我的问题是。。。为了过滤/替换值,我可以改变创建图的最后一位吗 groupby