将总计和计数行添加到数据框

Question

我有一个数据框，如下所示：

dashboard = pd.DataFrame({
 'id':[1,2,3,4],
 'category': ['a', 'b', 'a', 'c'],
 'price': [123, 151, 21, 24],
 'description': ['IT related', 'IT related', 'Marketing','']
})

我需要添加一行以仅显示某些类别的总和和计数，如下所示：

pd.DataFrame({
 'id': [3],
 'category': ['a&b'],
 'price': [295],
 'description': ['']
})

Answer 1

使用.agg的选项：

dashboard = pd.DataFrame({
    'id': [1, 2, 3, 4],
    'category': ['a', 'b', 'a', 'c'],
    'price': [123, 151, 21, 24],
    'description': ['IT related', 'IT related', 'Marketing', '']
})
a_b = dashboard[dashboard['category'].isin(['a','b'])].agg({'id':'count', 'price':sum})
df = pd.DataFrame({'a&b':a_b})

收益

       a&b
id       3
price  295

然后您可以.transpose()，然后根据需要合并到现有的数据框中，或者编译汇总结果的单独数据框，等等。

Answer 2

我预先计算了每个类别的所有总和，然后为每对货币总和加上类别名称，并添加新行。

尝试一下：

import pandas as pd

dashboard = pd.DataFrame({
    'id': [1, 2, 3, 4],
    'category': ['a', 'b', 'a', 'c'],
    'price': [123, 151, 21, 24],
    'description': ['IT related', 'IT related', 'Marketing', '']
})

pairs = [('a', 'b')]

groups = dashboard.groupby("category")['price'].sum()

for c1, c2 in pairs:
    new_id = sum((dashboard['category'] == c1) | (dashboard['category'] == c2))
    name = '{}&{}'.format(c1, c2)
    price_sum = groups[c1] + groups[c2]
    dashboard = dashboard.append(pd.DataFrame({'id': [new_id], 'category': [name], 'price': [price_sum], 'description': ['']}))

print(dashboard)

Answer 3

尝试：

代码

dashboard = pd.DataFrame({
 'id':[1,2,3,4],
 'category': ['a', 'b', 'a', 'c'],
 'price': [123, 151, 21, 24],
 'description': ['IT related', 'IT related', 'Marketing','']
})

selection =['a','b']
selection_row = '&'.join(selection)
df2 = dashboard[dashboard['category'].isin(selection)].agg({'id' : ['count'], 'price' : ['sum']}).fillna(0).T
df2['summary'] = df2['count'].add(df2['sum'])

df2.loc['description'] =np.nan
df2.loc['category'] = selection_row

final_df = df2['summary']

final_df

id               3
price          295
description    NaN
category       a&b
Name: summary, dtype: object