dplyr包summarize的使用

dat<-mtcars

dat1<-group_by(dat,cyl,gear)
summarize(dat1)

# A tibble: 8 x 2
# Groups:   cyl [3]
    cyl  gear
  <dbl> <dbl>
1     4     3
2     4     4
3     4     5
4     6     3
5     6     4
6     6     5
7     8     3
8     8     5

summarise(dat1, Q1 = quantile(disp, 0.25), ME = median(disp), Q3 = quantile(disp, 0.75))

    cyl  gear    Q1    ME    Q3
  <dbl> <dbl> <dbl> <dbl> <dbl>
1     4     3 120.  120.   120.
2     4     4  78.0  93.5  126.
3     4     5 101.  108.   114 
4     6     3 233.  242.   250.
5     6     4 160   164.   168.
6     6     5 145   145    145 
7     8     3 297.  355    410 
8     8     5 314.  326    338.