I have a few problems using append in python

Question

I have a few problems using append in python This is my code

import requests
from bs4 import BeautifulSoup
import lxml
import csv

def get_html(url):
    try:
        r = requests.get(url)
        r.raise_for_status()
        r.encoding = r.apparent_encoding  # utf-8
        return r.text
    except:
        r = "fail"
        return r
    
def getGDP(ulist,html):
    soup = BeautifulSoup(html,"html.parser")
    trs = soup.find_all('tr')    
    for tr in trs:
        list = []    
        for th in tr:   
            ts = th.string    
            if ts == '\n':
                continue
            list.append(ts)
        ulist.append(list)
        
def saveGDP(ulist):
        file_name = '21095010 胡碧玉 GDP.csv'
        with open(file_name,'a',errors='ignore',newline='') as f:
                f_csv = csv.writer(f)
                f_csv.writerows(ulist)
        
def main():  
    for i in range (1):
        unifo=[]    
        url='https://www.kylc.com/stats/global/yearly_per_country/g_gdp/vnm.html'
        html=get_html(url)    
        getGDP(unifo,html)
        saveGDP(unifo)    

if __name__=="__main__":
    main()

i want to get GDP data from a country.

It works, but when I run the code again, the result is then appended to the previous one. it has duplicate results.

I want the result to always show one record, not duplicate records

Answer 1

I think you can try changing open parameters in saveGDP method to open(file_name,'w',errors='ignore',newline='') so that it will write brand new data from the server you scrape every time it is run. You can see more about the open method modes here