AttributeError: 'NoneType' object has no attribute 'assign'

I am trying to access data using web-scraping and making it into a data frame using pandas. With the following code, I am already able to get the data frame. I want to combine all the data frames with append into one large data frame.

import requests
import re
import pandas as pd
from urllib.parse import unquote
from json import loads
from bs4 import BeautifulSoup

# Download URL
url = "https://riwayat-file-covid-19-dki-jakarta-jakartagis.hub.arcgis.com/"
req = requests.get(url)

# Get encoded JSON from HTML source
encoded_data = re.search("window\.__SITE=\"(.*)\"", req.text).groups()[0]

# Decode and load as dictionary
json_data = loads(unquote(encoded_data))

# Get the HTML source code for the links
html_src = json_data["site"]["data"]["values"]["layout"]["sections"][1]["rows"][0]["cards"][0]["component"]["settings"]["markdown"]

# Parse it using BeautifulSoup
soup = BeautifulSoup(html_src, 'html.parser')

# Get links
links = soup.find_all('a')

# For each link...
link_list = []
id_list = []
date_list = []
dataframe_csv = []

for link in links:
    if "2021" in link.text:
       link_list.append(link.text " - " link.attrs['href'])

link_list.remove("31 Januari 2021 Pukul 10.00 - https://drive.google.com/file/d/1vd1tToQbx3A420KMDA63aKviLjgGPJMd/view?usp=sharing")

for i in link_list:
    id_list.append(i.split("/")[5])
    date_list.append(i.split("/")[0][:-21])
    
for ID in id_list:
    dataframe_csv.append("https://docs.google.com/spreadsheets/d/" ID "/export?format=csv")

I want to combine all the data frames that I have by using a loop. For every loop, I want to remove the index 0 row and add a new column which is Date. The code is as follows:

date_num = 0
df_total = pd.DataFrame()

for i in dataframe_csv:
    df = pd.read_csv(i)
    df = df.drop(index=df.index[0], axis=0, inplace=True)
    df = df.assign(Date = date_list[date_num])
    
    date_num  = 1
    
    df_total.append(df,ignore_index=True)

The problem is, I get an error like this:

AttributeError                            Traceback (most recent call last)
<ipython-input-11-ef67f0a87a8e> in <module>
      5     df = pd.read_csv(i)
      6     df = df.drop(index=df.index[0], axis=0, inplace=True)
----> 7     df = df.assign(Date = date_list[date_num])
      8 
      9     date_num  = 1

AttributeError: 'NoneType' object has no attribute 'assign'

CodePudding user response：

inplace=True modifies the dataframe directly, so either remove it:

date_num = 0
df_total = pd.DataFrame()

for i in dataframe_csv:
    df = pd.read_csv(i)
    df = df.drop(index=df.index[0], axis=0)
    df = df.assign(Date = date_list[date_num])
    
    date_num  = 1
    
    df_total.append(df,ignore_index=True)

Or not assign it back:

date_num = 0
df_total = pd.DataFrame()

for i in dataframe_csv:
    df = pd.read_csv(i)
    df.drop(index=df.index[0], axis=0, inplace=True)
    df = df.assign(Date = date_list[date_num])
    
    date_num  = 1
    
    df_total.append(df,ignore_index=True)

As mentioned in the documentation of drop:

inplace : bool, default False
If False, return a copy. Otherwise, do operation inplace and return None.