Python - for循環，執行一個總和並在新列中存儲答案

Question

我想計算所有具有相同名稱的人的總年齡：請參閱此處的示例表。

table with names

這是迄今爲止我所編寫的代碼..但它是不完整的，這是行不通的..

final_df = DataFrame() 

for i in [list of names]: 
dummy = sort_df.loc[sort_df['name'] == i]  
total_age = 0 

for j in dummy.age:  
    age2 = dummy.age(j) 

    total_age = total_age + age2 

    final_df.append(total_age) 


final_df['total_age'] = total_age 

我該如何解決這個問題，我可以寫一個代碼可以迭代多個具有相同名稱的人並將它們相加並將它們存儲在一個新列中？

最後，它應該是這樣的：

Result

Answer 1

在你的代碼的樣子，我假設有具有名爲input.csv一個CSV文件已使用此數據讀取到sort_df：

name,age,total age 
Alfredo,13, 
Alfredo,12, 
Alfredo,15, 
Jaap,12, 
Jaap,14, 
Koen,16, 
Lian,76, 
Lian,45, 
Lian,34, 
Lian,14, 

在這種情況下，不需要聲明另一個dummy數據幀。使用此：

from pandas import DataFrame 

sort_df = DataFrame.from_csv("inCSV.txt", index_col=False) 
final_df = sort_df 

# Use a dictionary to keep track instead 
total_age = {} 
for name in sort_df["name"]: 
    if name not in total_age.keys(): 
     total_age[name] = 0 

# Add up the ages 
for index in xrange(len(sort_df)): 
    person = sort_df.loc[index] 
    name = person["name"] 
    age = person["age"] 
    total_age[name] += age 

# Set the new ages into final_df 
for index in xrange(len(final_df)): 
    person = final_df.loc[index] 
    name = person["name"] 
    final_df.set_value(index, "total age", total_age[name]) 

print final_df 

，這將給你（在final_df）：

 name age total age 
0 Alfredo 13  40.0 
1 Alfredo 12  40.0 
2 Alfredo 15  40.0 
3  Jaap 12  26.0 
4  Jaap 14  26.0 
5  Koen 16  16.0 
6  Lian 76  169.0 
7  Lian 45  169.0 
8  Lian 34  169.0 
9  Lian 14  169.0 

Answer 2

你在這裏找到了答案：

from collections import defaultdict 
list_name = [ 
{'age': 25, 'name': 'alfredo'}, 
{'age': 44, 'name': 'alfredo'}, 
{'age': 23, 'name': 'jaap'}, 
{'age': 60, 'name': 'jaap'} 
] 

k={} 
c = defaultdict(int) 
for d in list_name: 
    c[d['name']] += d['age'] 
    k[d['name']] = c[d['name']] 
for d in list_name: 
    d['total_age'] = k[d['name']] 
print list_name 

Answer 3

數據。例如，

name,age 
Alfredo,13, 
Alfredo,12, 
Alfredo,15, 
Jaap,12, 
Jaap,14, 
Koen,16, 
Lian,76, 
Lian,45, 
Lian,34, 
Lian,14, 

import csv 
from collections import defaultdict 
result = defaultdict(int) 
reader = csv.DictReader(csv_file_handle) 
for person in reader: 
    name = person['name'].lower() 
    age = int(person['age']) 
    result[name] += age 
>>> result 
defaultdict(int, {'alfredo': 40, 'jaap': 26, 'koen': 16, 'lian': 169}) 

要更新result

# make a reader object  
# make a writer object with fieldnames ['name', 'age', 'total_age'] 
# write header 
for person in reader: 
    person.update({'total_age': result[person['name'].lower()]}) 
    writer.writerow(person)