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)
| path | path to fst file |
|---|---|
| ft | An object of class fst_table, returned by |
| row_no | An integer vector (Positive) |
| ... | The filter conditions |
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 (filea5434c14328.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 virginicaclass(ft)#> [1] "fst_table"#> $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 5summary_fst(ft)#> <fst file> #> 150 rows, 5 columns (filea5434c14328.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#> 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 setosaft %>% 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: 5.9ft %>% 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 3.0ft %>% 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: 5.9ft %>% 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 5.1ft %>% 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 5.1ft %>% 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#> 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 5.1ft %>% 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 Speciesft %>% 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 Speciesft %>% 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