Pandas DataFrame 列内の連続する値をグループ化する方法は?

   a
0  1
1  1
2 -1
3  1
4 -1
5 -1

[1, 1]
[-1]
[1]
[-1, -1]

df = pd.DataFrame({'a': [1, 1, -1, 1, -1, -1]})
print(df)

# Create a series that identifies consecutive value breaks
breaks = df['a'].ne(df['a'].shift()).cumsum()
print(breaks)

# Group the DataFrame by the breaks series
for i, g in df.groupby(breaks):
    print(i)
    print(g)
    print(g.a.tolist())

1
   a
0  1
1  1
[1, 1]
2
   a
2 -1
[-1]
3
   a
3  1
[1]
4
   a
4 -1
5 -1
[-1, -1]