向Dataframe的部分添加行

Question

我希望从dataframe的第一部分添加行到dataframe的其他部分，同时更改一列中的值。

例如，如果我将以下内容作为我的输入数据帧：

Type     Color    Size    Dimensions
Circle   Blue     Large   2D
Circle   Green    Small   3D
Circle   Black    Large   2D
Square   Red      Large   2D
Square   White    Small   3D
Triangle Red      Large   2D
Triangle White    Small   3D

我想将Circle行添加到其他形状中(但将值circle替换为其各自的形状，无论是正方形还是三角形)，使其如下所示：

Type     Color    Size    Dimensions
Circle   Blue     Large   2D
Circle   Green    Small   3D
Circle   Black    Large   2D
Square   Red      Large   2D
Square   White    Small   3D
Square   Blue     Large   2D
Square   Green    Small   3D
Square   Black    Large   2D
Triangle Red      Large   2D
Triangle White    Small   3D
Triangle Blue     Large   2D
Triangle Green    Small   3D
Triangle Black    Large   2D

有没有一种简单的方法可以通过group by或merge来做到这一点？

Answer 1

尝试：

# circle rows
circles = df.query('Type=="Circle"')

pd.concat([df] + [circles.assign(Type=t) for t in df.Type.unique() if t!='Circle'])

输出：

       Type  Color   Size Dimensions
0    Circle   Blue  Large         2D
1    Circle  Green  Small         3D
2    Circle  Black  Large         2D
3    Square    Red  Large         2D
4    Square  White  Small         3D
5  Triangle    Red  Large         2D
6  Triangle  White  Small         3D
0    Square   Blue  Large         2D
1    Square  Green  Small         3D
2    Square  Black  Large         2D
0  Triangle   Blue  Large         2D
1  Triangle  Green  Small         3D
2  Triangle  Black  Large         2D