如果第一个值匹配，则求和值

Question

Is there any way i can compare both lists and sum the second value ONLY if the the first value matches? I queried two tables and gave me the results below but not sure if python has some sort of group function i can use to group the account number(first value) and sum the second values if the first value matches.

import psycopg2

def connect():
    conn = psycopg2.connect(host="test", port=5432, database="test", user="test", 
    password="test123")
    cursor = conn.cursor()
    return cursor

def allocation(cursor,cashdt, sumbmaster):
    alloclist = []
    print("Allocation: ")
    cursor.execute("""select bill_acct,sum(debit_amount) from test.a where 
    cash_date ='"""
               + cashdt + "'" + "and master_bill='" + sumbmaster +"' group by bill_acct")
    for row in cursor.fetchall():
         a = row[0],"{:.2f}".format(row[1])
         alloclist.append(a)
     print(alloclist)

 def statement(cursor, billingdt,sumbmaster):
     statementlist = []
     cursor.execute(
         """
         select bill_account,total_due_amount from test.b where billing_date ='""" 
     + billingdt + "'" + "and master_bill='" + sumbmaster + "'")
     print("Statement:")
    for row in cursor.fetchall():
         a = row[0], "{:.2f}".format(row[1])
         statementlist.append(a)
     print(statementlist)

def main():
    connect()
    allocation(connect(),'2020-02-25','123')
    statement(connect(), '2020-2-14', '345')

example

list 1 =[('123',1),('345', 2)]
list2 = [('123',1),('345', 2)]

output

('123',2), ('345',4)

Answer 1

Is there any way i can compare both lists and sum the second value ONLY if the the first value matches?

Yes:

if list1[0] == list2[0]:
    result = list1[1] + list2[1]

Answer 2

使用列表理解

[(i[0],i[1]+j[1]) for i,j in zip(list1,list2) if i[0]==j[0]]