pandas 除一个外，所有行总和与熊猫
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All row sum with pandas except one
提问by Glori P.
I have several tables on a PostgreSQL database that look more or less like that:
我在 PostgreSQL 数据库上有几个表，看起来或多或少是这样的：
gid col2 col1 col3
6 15 45 77
1 15 45 57
2 14 0.2 42
3 12 6 37
4 9 85 27
5 5 1 15
For each table, numbers and columns' names change (I created them in a loop in python).
对于每个表，数字和列的名称都会发生变化（我在 python 中循环创建了它们）。
I would like to have back another column called sum for each table with the sum of each calumn except for the gid. The goal is having something like that:
我想为每个表返回另一个名为 sum 的列，其中包含除 gid 之外的每个 calumn 的总和。目标是有这样的东西：
gid col2 col1 col3 sum
6 15 45 77 137
1 15 45 57 117
2 14 0.2 42 56.2
3 12 6 37 55
4 9 85 27 121
5 5 1 15 21
I cannot use column name: the only one with no changes is gid.
我不能使用列名：唯一没有改变的是gid.
Some idea to make it with python(pandas, numpy) or psql?
用python( pandas, numpy) 或psql?
回答by jezrael
df['sum'] = df.drop('gid', axis=1).sum(axis=1)
print (df)
gid col2 col1 col3 sum
0 6 15 45.0 77 137.0
1 1 15 45.0 57 117.0
2 2 14 0.2 42 56.2
3 3 12 6.0 37 55.0
4 4 9 85.0 27 121.0
5 5 5 1.0 15 21.0
If gidis always first column, select by ilocall columns without first and then sumthem:
如果gid始终是第一列，则按iloc所有列选择，而不是先选择，然后选择sum它们：
df['sum'] = df.iloc[:, 1:].sum(axis=1)
print (df)
gid col2 col1 col3 sum
0 6 15 45.0 77 137.0
1 1 15 45.0 57 117.0
2 2 14 0.2 42 56.2
3 3 12 6.0 37 55.0
4 4 9 85.0 27 121.0
5 5 5 1.0 15 21.0
