Python根据一列的唯一值创建多个列

account_id, campaign_objective, campaign_spend, conversions
__________, __________________, ______________, ___________
1,          sales,              100,            25
1,          brand,              50,             25
2,          sales,              80,             12
2,          brand,              60,             12

我想做的是为每个独特的campaign_目标创建一列,并为其分配相应的支出价值。

account_id, sales, brand, conversions
__________, _____, _____, ___________
1,          100,   50,    25
2,          80,    60,    12 

我的方法一直用于循环和字典。这是次优的,因为我的数据帧中有2000万行,有100个campaign\u目标;换句话说,我的for循环需要迭代20亿个值。

new_df = {'account_id':[], 'conversions':[]}
for obj in obj_goal_list:
    new_df.update({obj:[]})

for acct in df['account_id'].unique():
    acct_df = df[df['account_id']==acct]
    new_df['account_id'].append(acct)
    new_df['conversions'].append(acct_df['conversions'])

    for obj in obj_goal_list: 
        if obj in acct_df['objective_and_goal']:
            spend = acct_df[acct_df['objective_and_goal']==obj]['spend']
            new_df[obj].append(spend)
        else:
            new_df[obj].append(0.0)
new_df = pd.DataFrame(new_df)

我很好奇,是否有更“熊猫”的方式来实现这一点,通过枢轴或其他方式?