r - 创建一个范围内有间隙的序列

Question

我正在尝试在一个范围内创建一个数字序列，每第四个数字跳过一次。我知道它可能涉及seq或seq_len以某种方式，但我似乎无法弄清楚。

顺序应该是这样的：

c(1,2,3,5,6,7,9,10,11...48)

Answer 1

另外的选择：

x <- 1:48
x[-seq.int(0L, length(x), 4L)]

---

基准

x <- 1:48e6

library(microbenchmark)
mbm <- microbenchmark(
  steven    = x[-seq.int(0L, length(x), 4L)],
  venyao    = x[x %% 4 != 0],
  venyao2   = as.vector(matrix(x, nrow=4)[-4, ]),
  pascal    = x[as.logical((x) %% 4)],
  user20650 = as.integer(matrix(x, nrow=4)[-4, ]),
  times = 10
)

#Unit: milliseconds
#      expr       min        lq      mean    median        uq       max neval  cld
#    steven  326.2159  350.6567  354.2743  357.3672  359.9924  368.3123    10 a   
#    venyao 1388.9975 1395.8814 1417.3213 1400.1432 1455.2255 1470.7743    10    d
#   venyao2  613.9878  637.5377  639.1718  637.9342  640.1753  657.6627    10  b  
#    pascal 1236.6055 1243.8149 1265.1976 1249.1046 1304.5699 1316.8247    10   c 
# user20650  587.8511  596.5614  610.4037  602.3607  619.1915  670.8756    10  b  

Answer 2

x <- 1:48
x[x%%4!=0]
# [1]  1  2  3  5  6  7  9 10 11 13 14 15 17 18 19 21 22 23 25 26 27 29 30 31 33 34 35
# [28] 37 38 39 41 42 43 45 46 47

更新： 我发现了一种更快的方法。

x <- 1:48e6
mbm <- microbenchmark(
 steven = x[-seq.int(0L, length(x), 4L)],
 venyao1 = x[x %% 4 != 0],
 venyao2 = as.vector(matrix(x, nrow=4)[-4, ]),
 pascal = x[as.logical((x) %% 4)],
 times = 10
)

mbm
# Unit: milliseconds
#    expr       min        lq      mean    median        uq      max neval
# steven 1519.4170 1524.0044 1553.3609 1554.0616 1554.7951 1639.989    10
# venyao1 3323.2142 3327.3154 3382.2387 3369.9388 3426.3029 3502.881    10
# venyao2  919.8674  921.3917  932.3078  923.1563  923.6811 1007.784    10   
# pascal 3207.6932 3211.9832 3245.4686 3213.5090 3299.4639 3356.368    10