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Just a simple use of DataFrames.  Looking for a new flashlight, I decided to compile a small selection of flashlights for comparison.
 

interface(rtablesize = 20)

Type := `<,>`(LED, LED, LED, Incandescent, Incandescent)``

BType := `<,>`(AAA, AA, AAA, AA, AAA)

Make := `<,>`(Maglite, Maglite, Maglite, Maglite, Maglite)

Batteries := `<,>`(1, 2, 3, 2, 1)

Lumens := `<,>`(47, 245, 200, 14, 2)

Model := `<,>`(Solitaire, `Pro+`, XL50, mini, Solitaire)

Minutes := `<,>`(105, 135, 405, 315, 225)

Cost := `<,>`(17.49, 41, 46.99, 16.50, 10)

NULL

Note:The values for cost used is in Canadian dollars, and the stores for the prices taken were from the following - MEC, Lowes, Canadian Tire and Amazon.ca

NULL

NULL

NULL

Flashlight := DataFrame(`<|>`(Make, Model, Type, BType, Batteries, Lumens, Minutes, Cost), columns = `<,>`("Make", "Model", "Type", "BType", "Batteries", "Lumens", "Minutes", "Cost"))

_m652460160

 (1)

NULL

numelems(Flashlight)

40

 (2)

sort(Flashlight, "Cost")

_m653259008

 (3)

sort(Flashlight, "Lumens")

_m629071232

 (4)

NULL

No surprise that the cheapest and lowest light outputs were incandescent flashlights.  The list isn't very large so lets add a few more flashlights to our list

NULL

new1 := DataFrame(`<,>`(`<|>`(Thrunite, Ti3, LED, AAA, 1, 130, 30, 26.95), `<|>`(Police*Security, Stealth, LED, AA, 1, 80, 60, 7.99), `<|>`(Police*Security, Shield, LED, AA, 1, 120, 90, 15.99), `<|>`(Fenix, E12, LED, AA, 1, 130, 90, 37), `<|>`(Fenix, E20, LED, AA, 2, 265, 30, 50.75), `<|>`(Fenix, E05, LED, AAA, 1, 85, 45, 31.99), `<|>`(Maglite, mini, LED, AAA, 2, 84, 345, 22)), 'columns' = ["Make", "Model", "Type", "BType", "Batteries", "Lumens", "Minutes", "Cost"], 'rows' = [6, 7, 8, 9, 10, 11, 12])

_m624778752

 (5)

F1 := Append(Flashlight, new1)

_m647087136

 (6)

sort(F1, "Cost")

_m627084608

 (7)

F2 := convert(sort(F1, "Cost", `<`), DataFrame)

_m650479744

 (8)

Interesting to note that Police Security generally seems to be the cheapest.

 

 

sort(F2, "BType")

_m629097504

 (9)

 

 

Adding yet more flashlights

 

new2 := DataFrame(`<,>`(`<|>`(Pelican, 1910*Gen3, LED, AAA, 1, 106, 150, 38), `<|>`(Pelican, 1920*Gen3, LED, AAA, 2, 224, 135, 41)), 'columns' = ["Make", "Model", "Type", "BType", "Batteries", "Lumens", "Minutes", "Cost"], 'rows' = [13, 14])

_m629911872

 (10)

F3 := Append(F2, new2)

_m625417184

 (11)

sort(F3, "Cost")

_m641386752

 (12)

NULL

Now lets select just the Maglite models

 

F3[`~`[`=`](F3[() .. (), "Make"], Maglite)]

_m650462944

 (13)

``

Or select the flashlights that have a burn time longer than 100 minutes

 

F3[`~`[`>`](F3[() .. (), "Minutes"], 100)]

_m689998912

 (14)

NULL


 

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