假设我有一个看起来像这样的任意numpy矩阵:
arr = [[ 6.0 12.0 1.0]
[ 7.0 9.0 1.0]
[ 8.0 7.0 1.0]
[ 4.0 3.0 2.0]
[ 6.0 1.0 2.0]
[ 2.0 5.0 2.0]
[ 9.0 4.0 3.0]
[ 2.0 1.0 4.0]
[ 8.0 4.0 4.0]
[ 3.0 5.0 4.0]]
什么是平均按第三列编号分组的行的有效方法？
预期的产出是:
result = [[ 7.0 9.33 1.0]
[ 4.0 3.0 2.0]
[ 9.0 4.0 3.0]
[ 4.33 3.33 4.0]]