avg aggregation recipe missed in recipe.py

All the aggregations are present except avg aggregation -created a pull request and made the modifications.
Also can you suggest a way to do select columns from a particular dataset and also after the aggregation the column names are coming as columnname_aggregationname - is there any way to give a name to the aggregated column directly instead of going about modifying the output dataset?
Thanks.

从 recipe.py 开始，issue 指出其中缺少 avg 聚合。检查现有的聚合定义和报告的修改，然后确认 avg 是否与其他聚合一样可用。issue 还将列选择和聚合列命名作为单独的问题提出，因此在扩大范围之前需要先澄清这些问题。