Cut by Defined Interval

To cut unto pre-defined intervals, you can specify a vector of breaks using the breaks parameter.

Define some data:

x <- sample(0:20, 100, replace=TRUE)
x

Now cut x at 0, 10 and 20:

cut(x, breaks=c(0, 10, 20), include.lowest=TRUE)

  [1] (10,20] [0,10]  [0,10]  (10,20] (10,20] (10,20] [0,10]  (10,20] (10,20]
 [10] (10,20] [0,10]  (10,20] (10,20] (10,20] [0,10]  (10,20] [0,10]  [0,10] 
 [19] [0,10]  (10,20] [0,10]  [0,10]  [0,10]  (10,20] [0,10]  (10,20] (10,20]
 [28] (10,20] (10,20] [0,10]  [0,10]  [0,10]  [0,10]  (10,20] [0,10]  [0,10] 
 [37] [0,10]  [0,10]  (10,20] (10,20] (10,20] (10,20] [0,10]  (10,20] [0,10] 
 [46] (10,20] [0,10]  (10,20] (10,20] [0,10]  [0,10]  (10,20] (10,20] (10,20]
 [55] [0,10]  [0,10]  (10,20] [0,10]  [0,10]  [0,10]  [0,10]  (10,20] (10,20]
 [64] (10,20] [0,10]  [0,10]  (10,20] (10,20] (10,20] (10,20] (10,20] (10,20]
 [73] (10,20] [0,10]  [0,10]  [0,10]  (10,20] [0,10]  (10,20] [0,10]  (10,20]
 [82] [0,10]  [0,10]  (10,20] [0,10]  [0,10]  [0,10]  (10,20] (10,20] [0,10] 
 [91] [0,10]  [0,10]  (10,20] (10,20] [0,10]  [0,10]  [0,10]  [0,10]  (10,20]
[100] (10,20]
Levels: [0,10] (10,20]

Something like this? Breaks for each 0.2 from 0 to 1.

> a <- runif(100)
> cut(a, seq(from = 0, to = 1, by = 0.2))
  [1] (0,0.2]   (0.8,1]   (0.8,1]   (0.6,0.8] (0.6,0.8] (0,0.2]   (0.6,0.8]
  [8] (0.2,0.4] (0.8,1]   (0.4,0.6] (0.8,1]   (0.4,0.6] (0.8,1]   (0.6,0.8]
 [15] (0.8,1]   (0,0.2]   (0.8,1]   (0.8,1]   (0.6,0.8] (0.6,0.8] (0.2,0.4]
 [22] (0.4,0.6] (0.6,0.8] (0.2,0.4] (0.6,0.8] (0.6,0.8] (0.6,0.8] (0,0.2]  
 [29] (0,0.2]   (0.2,0.4] (0,0.2]   (0,0.2]   (0,0.2]   (0,0.2]   (0,0.2]  
 [36] (0.6,0.8] (0.2,0.4] (0.6,0.8] (0.6,0.8] (0.8,1]   (0.2,0.4] (0.4,0.6]
 [43] (0.4,0.6] (0.6,0.8] (0.2,0.4] (0.6,0.8] (0.6,0.8] (0.6,0.8] (0.4,0.6]
 [50] (0.6,0.8] (0.6,0.8] (0,0.2]   (0.2,0.4] (0.8,1]   (0.8,1]   (0.8,1]  
 [57] (0.6,0.8] (0.2,0.4] (0.2,0.4] (0,0.2]   (0.8,1]   (0.8,1]   (0.2,0.4]
 [64] (0.8,1]   (0.2,0.4] (0.4,0.6] (0.8,1]   (0,0.2]   (0.4,0.6] (0,0.2]  
 [71] (0.4,0.6] (0.8,1]   (0.6,0.8] (0.4,0.6] (0,0.2]   (0.2,0.4] (0.4,0.6]
 [78] (0,0.2]   (0.2,0.4] (0.8,1]   (0,0.2]   (0.4,0.6] (0.8,1]   (0,0.2]  
 [85] (0,0.2]   (0.2,0.4] (0.2,0.4] (0.4,0.6] (0.8,1]   (0.2,0.4] (0,0.2]  
 [92] (0.6,0.8] (0.2,0.4] (0.2,0.4] (0.8,1]   (0.2,0.4] (0.4,0.6] (0,0.2]  
 [99] (0,0.2]   (0,0.2]  
Levels: (0,0.2] (0.2,0.4] (0.4,0.6] (0.6,0.8] (0.8,1]