弄清楚了.

每列的最小值和最大值:

Minimum and maximum of every column:

apply(a,2,min)
apply(a,2,max)

每行的最小值和最大值:

Minimum and maximum of every row:

apply(a,1,min)
apply(a,1,max)

在此处找到信息 http://www.personality-project.org/r/r.commands.html