熊猫：如何按列选择第一个或最后一个与 drop_duplicates 保持一致

Question

As shown below, name must be keep in fisrt and team in last .

How can I accomplish this with .drop_duplicates() or otherwise?

   name  team ...
0  john  a    ...
1  mike  b    ...
2  john  c

↓

   name  team ...
0  john  c    ...
1  mike  b    ...

-- Additional note about comments --

.groupby('name').agg({'team': 'last', 'country': 'first'})

The way it works now, if the first line of country is Nan If the first line of country is Nan, a value that is not the first will be obtained as follows.

Is this because the case of Nan is ignored? Even if first is specified and first is Nan , Nan must still be retained.

   name  team  country ...
0  john   a    Nan     ...
1  mike  b     Brazil  ...
2  john  c     Canada  ...

↓

   name  team  country ...
0  john  c     Canada  ...
1  mike  b     Brazil  ...

Answer 1

You can use the .groupby() function:

df.groupby('name').agg({'team': 'last'}) .

Be aware that in the value that's returned per name is dependent on the sorting of your dataframe.