An API for reading fst file as data.table.
parse_fst(path)
slice_fst(ft, row_no)
select_fst(ft, ...)
filter_fst(ft, ...)
summary_fst(ft)parse_fst returns a fst_table class.
select_fst and filter_fst returns a data.table.
summary_fst could provide some basic information about
the fst table.
# write the file first
path = tempfile(fileext = ".fst")
fst::write_fst(iris,path)
# parse the file but not reading it
parse_fst(path) -> ft
ft
#> <fst file>
#> 150 rows, 5 columns (file333c73e02ce5.fst)
#>
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <double> <double> <double> <double> <factor>
#> 1 5.1 3.5 1.4 0.2 setosa
#> 2 4.9 3.0 1.4 0.2 setosa
#> 3 4.7 3.2 1.3 0.2 setosa
#> 4 4.6 3.1 1.5 0.2 setosa
#> 5 5.0 3.6 1.4 0.2 setosa
#> -- -- -- -- -- --
#> 146 6.7 3.0 5.2 2.3 virginica
#> 147 6.3 2.5 5.0 1.9 virginica
#> 148 6.5 3.0 5.2 2.0 virginica
#> 149 6.2 3.4 5.4 2.3 virginica
#> 150 5.9 3.0 5.1 1.8 virginica
class(ft)
#> [1] "fst_table"
lapply(ft,class)
#> $Sepal.Length
#> [1] "numeric"
#>
#> $Sepal.Width
#> [1] "numeric"
#>
#> $Petal.Length
#> [1] "numeric"
#>
#> $Petal.Width
#> [1] "numeric"
#>
#> $Species
#> [1] "factor"
#>
names(ft)
#> [1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species"
dim(ft)
#> [1] 150 5
summary_fst(ft)
#> <fst file>
#> 150 rows, 5 columns (file333c73e02ce5.fst)
#>
#> * 'Sepal.Length': double
#> * 'Sepal.Width' : double
#> * 'Petal.Length': double
#> * 'Petal.Width' : double
#> * 'Species' : factor
# get the data by query
ft %>% slice_fst(1:3)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.9 3.0 1.4 0.2 setosa
#> 3: 4.7 3.2 1.3 0.2 setosa
ft %>% slice_fst(c(1,3))
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.7 3.2 1.3 0.2 setosa
ft %>% select_fst(Sepal.Length)
#> Sepal.Length
#> <num>
#> 1: 5.1
#> 2: 4.9
#> 3: 4.7
#> 4: 4.6
#> 5: 5.0
#> ---
#> 146: 6.7
#> 147: 6.3
#> 148: 6.5
#> 149: 6.2
#> 150: 5.9
ft %>% select_fst(Sepal.Length,Sepal.Width)
#> Sepal.Length Sepal.Width
#> <num> <num>
#> 1: 5.1 3.5
#> 2: 4.9 3.0
#> 3: 4.7 3.2
#> 4: 4.6 3.1
#> 5: 5.0 3.6
#> ---
#> 146: 6.7 3.0
#> 147: 6.3 2.5
#> 148: 6.5 3.0
#> 149: 6.2 3.4
#> 150: 5.9 3.0
ft %>% select_fst("Sepal.Length")
#> Sepal.Length
#> <num>
#> 1: 5.1
#> 2: 4.9
#> 3: 4.7
#> 4: 4.6
#> 5: 5.0
#> ---
#> 146: 6.7
#> 147: 6.3
#> 148: 6.5
#> 149: 6.2
#> 150: 5.9
ft %>% select_fst(1:3)
#> Sepal.Length Sepal.Width Petal.Length
#> <num> <num> <num>
#> 1: 5.1 3.5 1.4
#> 2: 4.9 3.0 1.4
#> 3: 4.7 3.2 1.3
#> 4: 4.6 3.1 1.5
#> 5: 5.0 3.6 1.4
#> ---
#> 146: 6.7 3.0 5.2
#> 147: 6.3 2.5 5.0
#> 148: 6.5 3.0 5.2
#> 149: 6.2 3.4 5.4
#> 150: 5.9 3.0 5.1
ft %>% select_fst(1,3)
#> Sepal.Length Petal.Length
#> <num> <num>
#> 1: 5.1 1.4
#> 2: 4.9 1.4
#> 3: 4.7 1.3
#> 4: 4.6 1.5
#> 5: 5.0 1.4
#> ---
#> 146: 6.7 5.2
#> 147: 6.3 5.0
#> 148: 6.5 5.2
#> 149: 6.2 5.4
#> 150: 5.9 5.1
ft %>% select_fst("Se")
#> Sepal.Length Sepal.Width
#> <num> <num>
#> 1: 5.1 3.5
#> 2: 4.9 3.0
#> 3: 4.7 3.2
#> 4: 4.6 3.1
#> 5: 5.0 3.6
#> ---
#> 146: 6.7 3.0
#> 147: 6.3 2.5
#> 148: 6.5 3.0
#> 149: 6.2 3.4
#> 150: 5.9 3.0
# return a warning with message
# \donttest{
ft %>% select_fst("nothing")
#> Warning: No matched columns,try other patterns. Names of the `fst_table` are listed.
#> [1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species"
# }
ft %>% select_fst("Se|Sp")
#> Sepal.Length Sepal.Width Species
#> <num> <num> <fctr>
#> 1: 5.1 3.5 setosa
#> 2: 4.9 3.0 setosa
#> 3: 4.7 3.2 setosa
#> 4: 4.6 3.1 setosa
#> 5: 5.0 3.6 setosa
#> ---
#> 146: 6.7 3.0 virginica
#> 147: 6.3 2.5 virginica
#> 148: 6.5 3.0 virginica
#> 149: 6.2 3.4 virginica
#> 150: 5.9 3.0 virginica
ft %>% select_fst(cols = names(iris)[2:3])
#> Sepal.Width Petal.Length
#> <num> <num>
#> 1: 3.5 1.4
#> 2: 3.0 1.4
#> 3: 3.2 1.3
#> 4: 3.1 1.5
#> 5: 3.6 1.4
#> ---
#> 146: 3.0 5.2
#> 147: 2.5 5.0
#> 148: 3.0 5.2
#> 149: 3.4 5.4
#> 150: 3.0 5.1
ft %>% filter_fst(Sepal.Width > 3)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.7 3.2 1.3 0.2 setosa
#> 3: 4.6 3.1 1.5 0.2 setosa
#> 4: 5.0 3.6 1.4 0.2 setosa
#> 5: 5.4 3.9 1.7 0.4 setosa
#> 6: 4.6 3.4 1.4 0.3 setosa
#> 7: 5.0 3.4 1.5 0.2 setosa
#> 8: 4.9 3.1 1.5 0.1 setosa
#> 9: 5.4 3.7 1.5 0.2 setosa
#> 10: 4.8 3.4 1.6 0.2 setosa
#> 11: 5.8 4.0 1.2 0.2 setosa
#> 12: 5.7 4.4 1.5 0.4 setosa
#> 13: 5.4 3.9 1.3 0.4 setosa
#> 14: 5.1 3.5 1.4 0.3 setosa
#> 15: 5.7 3.8 1.7 0.3 setosa
#> 16: 5.1 3.8 1.5 0.3 setosa
#> 17: 5.4 3.4 1.7 0.2 setosa
#> 18: 5.1 3.7 1.5 0.4 setosa
#> 19: 4.6 3.6 1.0 0.2 setosa
#> 20: 5.1 3.3 1.7 0.5 setosa
#> 21: 4.8 3.4 1.9 0.2 setosa
#> 22: 5.0 3.4 1.6 0.4 setosa
#> 23: 5.2 3.5 1.5 0.2 setosa
#> 24: 5.2 3.4 1.4 0.2 setosa
#> 25: 4.7 3.2 1.6 0.2 setosa
#> 26: 4.8 3.1 1.6 0.2 setosa
#> 27: 5.4 3.4 1.5 0.4 setosa
#> 28: 5.2 4.1 1.5 0.1 setosa
#> 29: 5.5 4.2 1.4 0.2 setosa
#> 30: 4.9 3.1 1.5 0.2 setosa
#> 31: 5.0 3.2 1.2 0.2 setosa
#> 32: 5.5 3.5 1.3 0.2 setosa
#> 33: 4.9 3.6 1.4 0.1 setosa
#> 34: 5.1 3.4 1.5 0.2 setosa
#> 35: 5.0 3.5 1.3 0.3 setosa
#> 36: 4.4 3.2 1.3 0.2 setosa
#> 37: 5.0 3.5 1.6 0.6 setosa
#> 38: 5.1 3.8 1.9 0.4 setosa
#> 39: 5.1 3.8 1.6 0.2 setosa
#> 40: 4.6 3.2 1.4 0.2 setosa
#> 41: 5.3 3.7 1.5 0.2 setosa
#> 42: 5.0 3.3 1.4 0.2 setosa
#> 43: 7.0 3.2 4.7 1.4 versicolor
#> 44: 6.4 3.2 4.5 1.5 versicolor
#> 45: 6.9 3.1 4.9 1.5 versicolor
#> 46: 6.3 3.3 4.7 1.6 versicolor
#> 47: 6.7 3.1 4.4 1.4 versicolor
#> 48: 5.9 3.2 4.8 1.8 versicolor
#> 49: 6.0 3.4 4.5 1.6 versicolor
#> 50: 6.7 3.1 4.7 1.5 versicolor
#> 51: 6.3 3.3 6.0 2.5 virginica
#> 52: 7.2 3.6 6.1 2.5 virginica
#> 53: 6.5 3.2 5.1 2.0 virginica
#> 54: 6.4 3.2 5.3 2.3 virginica
#> 55: 7.7 3.8 6.7 2.2 virginica
#> 56: 6.9 3.2 5.7 2.3 virginica
#> 57: 6.7 3.3 5.7 2.1 virginica
#> 58: 7.2 3.2 6.0 1.8 virginica
#> 59: 7.9 3.8 6.4 2.0 virginica
#> 60: 6.3 3.4 5.6 2.4 virginica
#> 61: 6.4 3.1 5.5 1.8 virginica
#> 62: 6.9 3.1 5.4 2.1 virginica
#> 63: 6.7 3.1 5.6 2.4 virginica
#> 64: 6.9 3.1 5.1 2.3 virginica
#> 65: 6.8 3.2 5.9 2.3 virginica
#> 66: 6.7 3.3 5.7 2.5 virginica
#> 67: 6.2 3.4 5.4 2.3 virginica
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
ft %>% filter_fst(Sepal.Length > 6 , Species == "virginica")
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 6.3 3.3 6.0 2.5 virginica
#> 2: 7.1 3.0 5.9 2.1 virginica
#> 3: 6.3 2.9 5.6 1.8 virginica
#> 4: 6.5 3.0 5.8 2.2 virginica
#> 5: 7.6 3.0 6.6 2.1 virginica
#> 6: 7.3 2.9 6.3 1.8 virginica
#> 7: 6.7 2.5 5.8 1.8 virginica
#> 8: 7.2 3.6 6.1 2.5 virginica
#> 9: 6.5 3.2 5.1 2.0 virginica
#> 10: 6.4 2.7 5.3 1.9 virginica
#> 11: 6.8 3.0 5.5 2.1 virginica
#> 12: 6.4 3.2 5.3 2.3 virginica
#> 13: 6.5 3.0 5.5 1.8 virginica
#> 14: 7.7 3.8 6.7 2.2 virginica
#> 15: 7.7 2.6 6.9 2.3 virginica
#> 16: 6.9 3.2 5.7 2.3 virginica
#> 17: 7.7 2.8 6.7 2.0 virginica
#> 18: 6.3 2.7 4.9 1.8 virginica
#> 19: 6.7 3.3 5.7 2.1 virginica
#> 20: 7.2 3.2 6.0 1.8 virginica
#> 21: 6.2 2.8 4.8 1.8 virginica
#> 22: 6.1 3.0 4.9 1.8 virginica
#> 23: 6.4 2.8 5.6 2.1 virginica
#> 24: 7.2 3.0 5.8 1.6 virginica
#> 25: 7.4 2.8 6.1 1.9 virginica
#> 26: 7.9 3.8 6.4 2.0 virginica
#> 27: 6.4 2.8 5.6 2.2 virginica
#> 28: 6.3 2.8 5.1 1.5 virginica
#> 29: 6.1 2.6 5.6 1.4 virginica
#> 30: 7.7 3.0 6.1 2.3 virginica
#> 31: 6.3 3.4 5.6 2.4 virginica
#> 32: 6.4 3.1 5.5 1.8 virginica
#> 33: 6.9 3.1 5.4 2.1 virginica
#> 34: 6.7 3.1 5.6 2.4 virginica
#> 35: 6.9 3.1 5.1 2.3 virginica
#> 36: 6.8 3.2 5.9 2.3 virginica
#> 37: 6.7 3.3 5.7 2.5 virginica
#> 38: 6.7 3.0 5.2 2.3 virginica
#> 39: 6.3 2.5 5.0 1.9 virginica
#> 40: 6.5 3.0 5.2 2.0 virginica
#> 41: 6.2 3.4 5.4 2.3 virginica
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
ft %>% filter_fst(Sepal.Length > 6 & Species == "virginica" & Sepal.Width < 3)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 6.3 2.9 5.6 1.8 virginica
#> 2: 7.3 2.9 6.3 1.8 virginica
#> 3: 6.7 2.5 5.8 1.8 virginica
#> 4: 6.4 2.7 5.3 1.9 virginica
#> 5: 7.7 2.6 6.9 2.3 virginica
#> 6: 7.7 2.8 6.7 2.0 virginica
#> 7: 6.3 2.7 4.9 1.8 virginica
#> 8: 6.2 2.8 4.8 1.8 virginica
#> 9: 6.4 2.8 5.6 2.1 virginica
#> 10: 7.4 2.8 6.1 1.9 virginica
#> 11: 6.4 2.8 5.6 2.2 virginica
#> 12: 6.3 2.8 5.1 1.5 virginica
#> 13: 6.1 2.6 5.6 1.4 virginica
#> 14: 6.3 2.5 5.0 1.9 virginica