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|Cu000.5 4601 1 26.50000 49.09998 45.200001 5
#> Evit000|Cu000.106 4757 3 26.89999 81.00000 129.000000 10
#> Evit000|Cu000.199 4856 6 32.00000 70.00000 75.200001 7
#> Evit000|Cu000.200 4856 6 32.00000 79.09998 91.700005 8
#> Evit000|Cu000.259 5497 8 21.20000 59.29999 68.000000 7
#> Evit000|Cu000.394 5852 12 23.79999 23.79999 NA 1
#> Evit000|Cu000.395 5852 12 23.79999 30.00000 9.700000 2
#> Evit000|Cu000.548 6287 18 21.50000 93.39996 146.599991 11
#> Evit000|Cu035.16 4602 1 28.29999 44.50000 26.100000 4
#> Evit000|Cu035.19 4602 1 28.29999 65.00000 72.800003 7
#> Evit000|Cu035.272 5500 8 17.00000 54.00000 87.000000 8
#> Evit000|Cu035.274 5500 8 17.00000 70.00000 124.800003 10
#> Evit000|Cu035.275 5500 8 17.00000 78.29999 147.300001 11
#> Evit000|Cu035.412 5862 11 22.00000 55.19998 62.000000 7
#> Evit000|Cu035.636 8049 20 22.00000 33.09998 19.900002 3
#> Evit000|Cu035.643 8049 20 22.00000 80.19995 137.600000 10
#> Evit000|Cu035.815 8273 22 25.00000 30.09999 8.000000 2
#> Evit000|Cu035.818 8273 22 25.00000 53.59998 48.500000 5
#> Evit000|Cu175.129 4760 3 15.00000 53.69998 83.800003 9
#> Evit000|Cu175.130 4760 3 15.00000 59.29999 93.200001 10
#> Evit000|Cu175.173 4817 4 24.59999 49.69998 47.000004 5
#> Evit000|Cu175.178 4817 4 24.59999 91.00000 144.000004 10
#> Evit000|Cu175.212 4857 6 26.00000 73.39996 101.800003 8
#> Evit000|Cu175.214 4857 6 26.00000 86.00000 135.300007 10
#> Evit000|Cu175.685 8139 23 24.00000 39.09998 30.300003 4
#> Evit000|Cu175.686 8139 23 24.00000 46.39999 45.100002 5
#> Evit000|Cu175.689 8139 23 24.00000 68.79999 91.800003 8
#> Evit000|Cu175.751 8192 21 35.39999 97.79999 165.000000 10
#> Evit100|Cu000.181 4854 6 29.00000 29.00000 NA 1
#> Evit100|Cu000.188 4854 6 29.00000 70.19995 86.200001 8
#> Evit100|Cu000.310 5524 9 22.39999 78.09998 136.099997 10
#> Evit100|Cu000.479 6058 16 27.39999 32.19998 8.100000 2
#> Evit100|Cu000.488 6058 16 27.39999 100.50000 148.600000 11
#> Evit100|Cu000.515 6211 17 24.50000 31.59999 8.100000 2
#> Evit100|Cu000.524 6211 17 24.50000 96.89996 146.500000 11
#> Evit100|Cu000.529 6284 18 23.09999 40.69998 30.600006 4
#> Evit100|Cu000.591 6433 5 32.19998 60.09998 58.600000 6
#> Evit100|Cu000.596 6433 5 32.19998 111.09998 163.000000 11
#> Evit100|Cu035.38 4605 1 31.50000 34.79999 6.500000 2
#> Evit100|Cu035.220 4858 6 28.00000 44.69998 31.800003 4
#> Evit100|Cu035.225 4858 6 28.00000 83.79999 133.200005 9
#> Evit100|Cu035.227 4858 6 28.00000 97.39996 190.800003 11
#> Evit100|Cu035.585 6432 5 25.09999 106.79999 197.400002 12
#> Evit100|Cu035.732 8191 21 26.59999 38.19998 20.000000 3
#> Evit100|Cu035.740 8191 21 26.59999 97.69995 162.800003 11
#> Evit100|Cu035.828 8437 24 27.00000 35.39999 16.400002 3
#> Evit100|Cu035.831 8437 24 27.00000 56.39999 54.900002 6
#> Evit100|Cu035.833 8437 24 27.00000 75.50000 88.500000 8
#> Evit100|Cu175.50 4641 2 27.09999 33.00000 5.200001 2
#> Evit100|Cu175.51 4641 2 27.09999 42.50000 22.500000 3
#> Evit100|Cu175.54 4641 2 27.09999 63.00000 69.800000 6
#> Evit100|Cu175.163 4815 4 24.89999 65.00000 80.100006 7
#> Evit100|Cu175.166 4815 4 24.89999 83.29999 149.000000 10
#> Evit100|Cu175.313 5527 9 26.59999 28.20000 10.000000 2
#> Evit100|Cu175.315 5527 9 26.59999 45.79999 50.000000 4
#> Evit100|Cu175.434 5866 11 22.00000 42.29999 36.800001 5
#> Evit100|Cu175.435 5866 11 22.00000 50.89999 49.800003 6
#> Evit100|Cu175.438 5866 11 22.00000 71.79999 93.800003 9
#> Evit200|Cu000.96 4756 3 17.00000 89.29999 163.700001 12
#> Evit200|Cu000.324 5528 9 24.00000 28.20000 10.000000 2
#> Evit200|Cu000.326 5528 9 24.00000 42.69998 32.100002 4
#> Evit200|Cu000.351 5581 10 27.00000 57.00000 59.900002 6
#> Evit200|Cu000.352 5581 10 27.00000 63.69998 76.100000 7
#> Evit200|Cu000.376 5850 12 22.79999 53.69998 60.200005 7
#> Evit200|Cu000.490 6207 17 27.09999 27.09999 NA 1
#> Evit200|Cu000.495 6207 17 27.09999 59.00000 57.200001 6
#> Evit200|Cu000.496 6207 17 27.09999 67.29999 72.100002 7
#> Evit200|Cu000.501 6207 17 27.09999 101.39996 153.800003 12
#> Evit200|Cu035.77 4645 2 27.70000 54.79999 55.200001 5
#> Evit200|Cu035.109 4759 3 22.59999 22.59999 NA 1
#> Evit200|Cu035.110 4759 3 22.59999 28.50000 10.600006 2
#> Evit200|Cu035.113 4759 3 22.59999 47.59998 47.100000 5
#> Evit200|Cu035.249 5392 7 24.59999 63.00000 89.499996 9
#> Evit200|Cu035.601 6909 13 24.70000 42.19998 26.600000 4
#> Evit200|Cu035.602 6909 13 24.70000 48.19998 38.000000 5
#> Evit200|Cu035.607 6909 13 24.70000 87.00000 116.900002 10
#> Evit200|Cu035.754 8193 21 29.29999 29.29999 NA 1
#> Evit200|Cu035.758 8193 21 29.29999 51.79999 51.000000 5
#> Evit200|Cu035.760 8193 21 29.29999 62.59998 86.200001 7
#> Evit200|Cu175.31 4603 1 27.59999 68.50000 80.500000 7
#> Evit200|Cu175.35 4603 1 27.59999 98.39996 145.000000 11
#> Evit200|Cu175.239 5389 7 24.29999 87.50000 131.100004 11
#> Evit200|Cu175.365 5582 10 29.50000 72.39996 86.800001 8
#> Evit200|Cu175.366 5582 10 29.50000 80.19995 105.200001 9
#> Evit200|Cu175.367 5582 10 29.50000 90.39996 127.800001 10
#> Evit200|Cu175.369 5582 10 29.50000 99.09998 167.500000 12
#> Evit200|Cu175.460 6056 16 32.50000 76.59998 89.000000 7
#> Evit200|Cu175.678 8053 20 21.89999 80.59998 138.000000 9
#> Evit200|Cu175.841 8439 24 27.29999 43.89999 33.200001 4