Allow use of formula to describe groups

[rpruim]

While refactoring for improved use of rlang, I think I have a way to support using a formula to describe groups.

Examples:

suppressPackageStartupMessages(library(mosaicCore))

df_stats( hp + mpg ~ cyl, groups = gear, data = mtcars, mean, median, range)
#>    response cyl gear     mean median range_1 range_2
#> 1        hp   4    3  97.0000  97.00    97.0    97.0
#> 2        hp   6    3 107.5000 107.50   105.0   110.0
#> 3        hp   8    3 194.1667 180.00   150.0   245.0
#> 4        hp   4    4  76.0000  66.00    52.0   109.0
#> 5        hp   6    4 116.5000 116.50   110.0   123.0
#> 6        hp   4    5 102.0000 102.00    91.0   113.0
#> 7        hp   6    5 175.0000 175.00   175.0   175.0
#> 8        hp   8    5 299.5000 299.50   264.0   335.0
#> 9       mpg   4    3  21.5000  21.50    21.5    21.5
#> 10      mpg   6    3  19.7500  19.75    18.1    21.4
#> 11      mpg   8    3  15.0500  15.20    10.4    19.2
#> 12      mpg   4    4  26.9250  25.85    21.4    33.9
#> 13      mpg   6    4  19.7500  20.10    17.8    21.0
#> 14      mpg   4    5  28.2000  28.20    26.0    30.4
#> 15      mpg   6    5  19.7000  19.70    19.7    19.7
#> 16      mpg   8    5  15.4000  15.40    15.0    15.8

df_stats( hp + mpg ~ cyl, groups = ~ gear, data = mtcars, mean, median, range)
#>    response cyl gear     mean median range_1 range_2
#> 1        hp   4    3  97.0000  97.00    97.0    97.0
#> 2        hp   6    3 107.5000 107.50   105.0   110.0
#> 3        hp   8    3 194.1667 180.00   150.0   245.0
#> 4        hp   4    4  76.0000  66.00    52.0   109.0
#> 5        hp   6    4 116.5000 116.50   110.0   123.0
#> 6        hp   4    5 102.0000 102.00    91.0   113.0
#> 7        hp   6    5 175.0000 175.00   175.0   175.0
#> 8        hp   8    5 299.5000 299.50   264.0   335.0
#> 9       mpg   4    3  21.5000  21.50    21.5    21.5
#> 10      mpg   6    3  19.7500  19.75    18.1    21.4
#> 11      mpg   8    3  15.0500  15.20    10.4    19.2
#> 12      mpg   4    4  26.9250  25.85    21.4    33.9
#> 13      mpg   6    4  19.7500  20.10    17.8    21.0
#> 14      mpg   4    5  28.2000  28.20    26.0    30.4
#> 15      mpg   6    5  19.7000  19.70    19.7    19.7
#> 16      mpg   8    5  15.4000  15.40    15.0    15.8

^{Created on 2020-07-03 by the reprex package (v0.3.0)}

[rpruim]

Working for tally() as well:

suppressPackageStartupMessages(library(mosaicCore))
tally(domhand ~ sex, groups = ~ biggerfoot, data = mosaicData::KidsFeet)
#> , , biggerfoot = L
#> 
#>        sex
#> domhand  B  G
#>       L  1  1
#>       R 10 10
#> 
#> , , biggerfoot = R
#> 
#>        sex
#> domhand  B  G
#>       L  4  2
#>       R  5  6

tally(domhand ~ sex, groups = ~ biggerfoot, data = mosaicData::KidsFeet, format = "data.frame")
#>   domhand sex biggerfoot Freq
#> 1       L   B          L    1
#> 2       R   B          L   10
#> 3       L   G          L    1
#> 4       R   G          L   10
#> 5       L   B          R    4
#> 6       R   B          R    5
#> 7       L   G          R    2
#> 8       R   G          R    6

^{Created on 2020-07-03 by the reprex package (v0.3.0)}

[rpruim]

Checking to make sure favstats() works this way now too:

suppressPackageStartupMessages(library(mosaicCore))
mosaic::favstats( length ~ sex, groups = ~ domhand, data = mosaicData::KidsFeet)
#> Registered S3 method overwritten by 'mosaic':
#>   method                           from   
#>   fortify.SpatialPolygonsDataFrame ggplot2
#>   domhand  min     Q1 median     Q3  max     mean        sd  n missing
#> 1     B.L 22.9 23.600  23.90 24.700 25.4 24.10000 0.9721111  5       0
#> 2     G.L 24.0 24.000  24.00 25.350 26.7 24.90000 1.5588457  3       0
#> 3     B.R 24.0 24.450  25.20 26.100 27.5 25.44000 1.1217334 15       0
#> 4     G.R 21.6 23.450  24.35 24.900 26.1 24.21250 1.3114242 16       0
#> 5       L 22.9 23.825  24.00 24.875 26.7 24.40000 1.1856282  8       0
#> 6       R 21.6 24.100  24.60 25.850 27.5 24.80645 1.3549749 31       0

mosaic::favstats( length ~ sex, groups = domhand, data = mosaicData::KidsFeet)
#>   domhand  min     Q1 median     Q3  max     mean        sd  n missing
#> 1     B.L 22.9 23.600  23.90 24.700 25.4 24.10000 0.9721111  5       0
#> 2     G.L 24.0 24.000  24.00 25.350 26.7 24.90000 1.5588457  3       0
#> 3     B.R 24.0 24.450  25.20 26.100 27.5 25.44000 1.1217334 15       0
#> 4     G.R 21.6 23.450  24.35 24.900 26.1 24.21250 1.3114242 16       0
#> 5       L 22.9 23.825  24.00 24.875 26.7 24.40000 1.1856282  8       0
#> 6       R 21.6 24.100  24.60 25.850 27.5 24.80645 1.3549749 31       0

^{Created on 2020-07-03 by the reprex package (v0.3.0)}