Python/Pandas Dataframe：自動填寫缺失的行

我的目標是最終在x軸上創建一個帶日期的散點圖，並贏得y軸上的代表（每個候選人）的代表。在缺少日期時，我不確定如何「填補空白」。我附上了我得到的表格的照片。Python/Pandas Dataframe：自動填寫缺失的行

例如，我試圖把3月1日作爲阿拉斯加州，阿肯色州等的日期，以便繪製數據。

# CREATE DATAFRAME WITH DELEGATE WON/TARGET INFORMATION 

import requests 
from lxml import html 
import pandas 

url = "http://projects.fivethirtyeight.com/election-2016/delegate-targets/" 
response = requests.get(url) 
doc = html.fromstring(response.text) 

tables = doc.findall('.//table[@class="delegates desktop"]') 
election = tables[0] 
election_rows = election.findall('.//tr') 
def extractCells(row, isHeader=False): 
    if isHeader: 
     cells = row.findall('.//th') 
    else: 
     cells = row.findall('.//td') 
    return [val.text_content() for val in cells] 


def parse_options_data(table): 

    rows = table.findall(".//tr") 
    header = extractCells(rows[1], isHeader=True) 
    data = [extractCells(row, isHeader=False) for row in rows[2:]] 

    trumpdata = "Trump Won Delegates" 
    cruzdata = "Cruz Won Delegates" 
    kasichdata = "Kasich Won Delegates" 

    data = pandas.DataFrame(data, columns=["Date", "State or Territory", "Total Delegates", trumpdata, cruzdata, kasichdata, "Rubio"]) 

    data.insert(4, "Trump Target Delegates", data[trumpdata].str.extract(r'(\d{0,3}$)')) 
    data.insert(6, "Cruz Target Delegates", data[cruzdata].str.extract(r'(\d{0,3}$)')) 
    data.insert(8, "Kasich Target Delegates", data[kasichdata].str.extract(r'(\d{0,3}$)')) 

    data = data.drop('Rubio', 1) 
    data[trumpdata] = data[trumpdata].str.extract(r'(^\d{0,3})') 
    data[cruzdata] = data[cruzdata].str.extract(r'(^\d{0,3})') 
    data[kasichdata] = data[kasichdata].str.extract(r'(^\d{0,3})') 

    return df 

election_data = parse_options_data(election) 
df = pandas.DataFrame(election_data) 
df

Picture of my table