<p>这个怎么样?你知道吗</p>
<pre><code># make main df
main = pd.DataFrame({'ColA' : ['xx', 'qs'],
'ColB' : ['yy', 'rr'],
'amount1' : [12, 13],
'amount2' : [1, 2],
'key' : ['55_ab', '14_rs']})
# make other df
df = pd.DataFrame({'ColA' : ['dd'],
'ColB' : ['tt'],
'amount1' : [10],
'amount2' : [5],
'key' : ['55_ab']})
# merge dataframes
df1 = main.merge(df,
how = 'left',
left_on = 'key',
right_on = 'key').fillna(0)
# sum amount1
df1.insert(df1.shape[1],
'amount1',
df1.amount1_x + df1.amount1_y)
# sum amount2
df1.insert(df1.shape[1],
'amount2',
df1.amount2_x + df1.amount2_y)
# drop unneeded columns
df1.drop(['amount1_x',
'amount2_x',
'ColA_y',
'ColB_y',
'amount1_y',
'amount2_y'],
axis = 1,
inplace = True)
</code></pre>
<p><a href="https://i.stack.imgur.com/DvgK2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DvgK2.png" alt="df"/></a></p>