A data frame is split according to some variables in a formula, and a sample of a certain fraction of each is drawn.
sample_by(data, formula, frac = 0.1, replace = FALSE, systematic = FALSE)
sampleBy(
formula,
frac = 0.1,
replace = FALSE,
data = parent.frame(),
systematic = FALSE
)A dataframe.
If systematic=FALSE (default) then frac gives the fraction of data sampled. If systematic=TRUE and frac=.2 then every 1/.2 i.e. every 5th observation is taken out.
data(dietox)
sampleBy(formula = ~ Evit + Cu, frac=.1, data = dietox)
#> Pig Litter Start Weight Feed Time
#> Evit000|Cu000.71 4643 2 27.00000 91.79999 148.400001 11
#> Evit000|Cu000.103 4757 3 26.89999 65.89996 78.300003 7
#> Evit000|Cu000.201 4856 6 32.00000 85.69995 109.000000 9
#> Evit000|Cu000.203 4856 6 32.00000 101.09998 153.000000 11
#> Evit000|Cu000.396 5852 12 23.79999 37.09998 20.800003 3
#> Evit000|Cu000.401 5852 12 23.79999 75.00000 94.800003 8
#> Evit000|Cu000.538 6287 18 21.50000 21.50000 NA 1
#> Evit000|Cu000.541 6287 18 21.50000 39.09998 27.800003 4
#> Evit000|Cu035.14 4602 1 28.29999 30.09999 3.300003 2
#> Evit000|Cu035.17 4602 1 28.29999 51.59998 43.600002 5
#> Evit000|Cu035.144 4813 4 27.29999 99.79999 182.100006 12
#> Evit000|Cu035.412 5862 11 22.00000 55.19998 62.000000 7
#> Evit000|Cu035.508 6208 17 26.79999 68.29999 73.700001 7
#> Evit000|Cu035.635 8049 20 22.00000 26.59999 9.500000 2
#> Evit000|Cu035.642 8049 20 22.00000 74.19995 116.000000 9
#> Evit000|Cu035.710 8142 23 25.20000 50.00000 44.000000 5
#> Evit000|Cu035.712 8142 23 25.20000 63.50000 73.100002 7
#> Evit000|Cu035.819 8273 22 25.00000 61.09998 67.000000 6
#> Evit000|Cu175.124 4760 3 15.00000 25.29999 22.100002 4
#> Evit000|Cu175.125 4760 3 15.00000 31.89999 29.900002 5
#> Evit000|Cu175.214 4857 6 26.00000 86.00000 135.300007 10
#> Evit000|Cu175.652 8050 20 26.79999 71.79999 89.900002 7
#> Evit000|Cu175.653 8050 20 26.79999 80.00000 111.000000 8
#> Evit000|Cu175.742 8192 21 35.39999 35.39999 NA 1
#> Evit000|Cu175.744 8192 21 35.39999 49.50000 29.800003 3
#> Evit000|Cu175.751 8192 21 35.39999 97.79999 165.000000 10
#> Evit000|Cu175.850 8442 24 25.70000 25.70000 NA 1
#> Evit000|Cu175.856 8442 24 25.70000 65.19995 66.000000 7
#> Evit100|Cu000.187 4854 6 29.00000 62.59998 70.000000 7
#> Evit100|Cu000.189 4854 6 29.00000 73.79999 100.000000 9
#> Evit100|Cu000.310 5524 9 22.39999 78.09998 136.099997 10
#> Evit100|Cu000.486 6058 16 27.39999 83.09998 104.800003 9
#> Evit100|Cu000.489 6058 16 27.39999 105.29999 166.900002 12
#> Evit100|Cu000.521 6211 17 24.50000 77.50000 96.200001 8
#> Evit100|Cu000.531 6284 18 23.09999 52.09998 53.400002 6
#> Evit100|Cu000.596 6433 5 32.19998 111.09998 163.000000 11
#> Evit100|Cu000.804 8271 22 24.00000 35.79999 19.500000 3
#> Evit100|Cu000.807 8271 22 24.00000 56.39999 56.600000 6
#> Evit100|Cu035.37 4605 1 31.50000 31.50000 NA 1
#> Evit100|Cu035.46 4605 1 31.50000 94.69995 133.100002 10
#> Evit100|Cu035.149 4814 4 26.20000 49.19998 37.400002 5
#> Evit100|Cu035.154 4814 4 26.20000 83.79999 127.400002 10
#> Evit100|Cu035.224 4858 6 28.00000 76.39996 107.300003 8
#> Evit100|Cu035.226 4858 6 28.00000 71.59998 163.100006 10
#> Evit100|Cu035.661 8051 20 30.59999 47.39999 31.100006 4
#> Evit100|Cu035.665 8051 20 30.59999 78.00000 95.800003 8
#> Evit100|Cu035.727 8144 23 23.50000 64.79999 96.000000 10
#> Evit100|Cu035.835 8437 24 27.00000 85.79999 119.500000 10
#> Evit100|Cu175.56 4641 2 27.09999 80.50000 101.100006 8
#> Evit100|Cu175.277 5501 8 30.00000 30.00000 NA 1
#> Evit100|Cu175.280 5501 8 30.00000 48.39999 35.200001 4
#> Evit100|Cu175.285 5501 8 30.00000 86.00000 110.000000 9
#> Evit100|Cu175.312 5527 9 26.59999 26.59999 NA 1
#> Evit100|Cu175.321 5527 9 26.59999 81.89996 136.999992 10
#> Evit100|Cu175.334 5578 10 27.09999 27.09999 NA 1
#> Evit100|Cu175.337 5578 10 27.09999 47.59998 45.300001 4
#> Evit100|Cu175.435 5866 11 22.00000 50.89999 49.800003 6
#> Evit100|Cu175.477 6057 16 27.00000 104.19995 165.400002 12
#> Evit200|Cu000.86 4756 3 17.00000 19.00000 9.900002 2
#> Evit200|Cu000.87 4756 3 17.00000 23.59999 18.500000 3
#> Evit200|Cu000.90 4756 3 17.00000 42.39999 52.799999 6
#> Evit200|Cu000.333 5528 9 24.00000 92.50000 146.100000 11
#> Evit200|Cu000.348 5581 10 27.00000 37.79999 19.500000 3
#> Evit200|Cu000.495 6207 17 27.09999 59.00000 57.200001 6
#> Evit200|Cu000.498 6207 17 27.09999 81.19995 103.200001 9
#> Evit200|Cu000.625 6912 13 24.50000 41.89999 29.500000 4
#> Evit200|Cu000.769 8195 21 25.29999 35.19998 28.000000 4
#> Evit200|Cu000.772 8195 21 25.29999 47.69998 69.000000 7
#> Evit200|Cu035.74 4645 2 27.70000 33.59998 10.000000 2
#> Evit200|Cu035.84 4645 2 27.70000 102.29999 180.000000 12
#> Evit200|Cu035.115 4759 3 22.59999 63.00000 80.800003 7
#> Evit200|Cu035.118 4759 3 22.59999 80.00000 128.900002 10
#> Evit200|Cu035.244 5392 7 24.59999 30.39999 29.999996 4
#> Evit200|Cu035.421 5865 11 22.00000 38.00000 29.200005 4
#> Evit200|Cu035.447 6055 16 26.20000 55.09998 62.200001 6
#> Evit200|Cu035.553 6288 18 24.09999 40.59998 30.800003 4
#> Evit200|Cu035.554 6288 18 24.09999 46.00000 40.900002 5
#> Evit200|Cu035.560 6288 18 24.09999 93.29999 141.000000 11
#> Evit200|Cu035.754 8193 21 29.29999 29.29999 NA 1
#> Evit200|Cu175.29 4603 1 27.59999 54.09998 50.000000 5
#> Evit200|Cu175.229 5389 7 24.29999 24.29999 NA 1
#> Evit200|Cu175.230 5389 7 24.29999 28.39999 5.400002 2
#> Evit200|Cu175.233 5389 7 24.29999 46.19998 41.800003 5
#> Evit200|Cu175.359 5582 10 29.50000 31.39999 6.800001 2
#> Evit200|Cu175.386 5851 12 22.29999 44.09998 39.000000 5
#> Evit200|Cu175.387 5851 12 22.29999 52.79999 56.000000 6
#> Evit200|Cu175.465 6056 16 32.50000 112.00000 191.400002 12
#> Evit200|Cu175.675 8053 20 21.89999 57.89999 71.400002 6
#> Evit200|Cu175.781 8269 22 22.09999 38.00000 27.400002 4