[英]Pandas Dataframe groupby two columns and sum up a column
I have pandas dataframe in the following format: 我有以下格式的pandas数据框:
d = {'buyer_code': ['A', 'B', 'C', 'A', 'A', 'B', 'B', 'A', 'C'], 'dollar_amount': ['2240.000', '160.000', '300.000', '10920.000', '10920.000', '235.749', '275.000', '10920.000', '300.000']}
df = pd.DataFrame(data=d)
df
This is how my dataframe looks like: 这是我的数据框的样子:
buyer_code dollar_amount
0 A 2240.000
1 B 160.000
2 C 300.000
3 A 10920.000
4 A 10920.000
5 B 235.749
6 B 275.000
7 A 10920.000
8 C 300.000
I have used groupby to list each buyer and there corresponding dollar amounts. 我使用groupby列出了每个买家,并列出了相应的美元金额。
df.groupby(['buyer_code', 'dollar_amount']).size()
This is the result: 结果如下:
buyer_code dollar_amount
A 10920.000 3
2240.000 1
B 160.000 1
235.749 1
275.000 1
C 300.000 2
dtype: int64
Now I want dollarAmount multiplied by its count and then sum of all the amounts for each buyer. 现在,我希望将dollarAmount乘以其计数,然后再乘以每个购买者的所有金额之和。
Lets say for example buyer_code "A" should have (10920.000 * 3) + (2240.000 * 1)
The result should be something like this: 结果应该是这样的:
buyer_code dollar_amount
A 35000
B 670.749
C 600.000
How can I get this output? 如何获得此输出?
Use groupby
+ aggregate sum
: 使用
groupby
+总sum
:
df['dollar_amount'] = df['dollar_amount'].astype(float)
a = df.groupby('buyer_code', as_index=False).sum()
print (a)
buyer_code dollar_amount
0 A 35000.000
1 B 670.749
2 C 600.000
unstack
your result, and then perform a matrix multiplication between the result and its columns with dot
- unstack
结果unstack
,然后在结果及其dot
之间用dot
进行矩阵乘法-
i = df.groupby(['buyer_code', 'dollar_amount']).size().unstack()
i.fillna(0).dot(i.columns.astype(float))
buyer_code
A 35000.000
B 670.749
C 600.000
dtype: float64
Or, 要么,
i.fillna(0).dot(i.columns.astype(float))\
.reset_index(name='dollar_amount')
buyer_code dollar_amount
0 A 35000.000
1 B 670.749
2 C 600.000
This is alright if you're doing something else with the intermediate groupby
result, necessitating the need for its computation. 如果您要对中间
groupby
结果执行其他操作,则需要进行计算,这没关系。 If not, a groupby
+ sum
makes more sense here. 如果不是,则
groupby
+ sum
在这里更有意义。
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