在R中，修复一个参数以使用lapply函数

This post contains two questions. The first is some related with the second. First, suppose that I want define one function that receives two arguments: one data frame and one variable(column) and I would like to do some counts or statistics. In first time, I have to determine the variable position. For example, suppose that my two first rows of the df areThis post contains two questions. The first is