How to implement a read table function in F#? (like Vlookup) - f#

Question

I need a function.
When I enter 0~15 and Protection, it'll return 45%.
Just like Vlookup function in Excel.
Is there a function like this one in F#?
(At website try F#, Learn -> Financial Modeling -> Using the Yahoo Finance Type Provider
It recommended us to use Samples.Csv.dll. However, I failed to install it and don't want to install that package just for a function :(.. )
I followed the tutorial (http://fsharp.github.io/FSharp.Data/library/CsvProvider.html)
and tried to run the program on my computer. But I am in trouble now
It couldn't identify the type CsvProvider (So I can't use the function Stocks.Load.)
What's the problem..?

Answer 1

This is how the code looks when using the CSV type provider in F# Data. To get this to work, you'll need to add reference to FSharp.Data.dll. The best way to do this is to install the package from NuGet. In Visual Studio, it will add reference for you, and in command line you can say:
nuget install FSharp.Data
Alternatively, if you are in an F# script file, then you need to install the nuget package and then add #r #"C:\path\to\FSharp.Data.dll". Then you can write the following:
open FSharp.Data
// Generate type based on a local copy with sample data
type Data = CsvProvider<"sample.csv">
// Load actual data from a file (this can be a different file with the same structure)
let loaded = Data.Load("runtime/file/name.csv")
// Find row for a specified age range & look at the properties
let row = loaded.Data |> Seq.find (fun r -> r.Age = "0~15")
row.Protection
row.Saving
row.Specified

Answer 2

A very simple way to do this is with a DataTable:
open System.Data
open System.IO
open LumenWorks.Framework.IO.Csv
let vlookup =
let table = new DataTable()
do
use streamReader = new StreamReader(#"C:\data.csv")
use csvReader = new CsvReader(streamReader, hasHeaders=true)
table.Load(csvReader)
table.PrimaryKey <- [|table.Columns.["Age"]|]
fun age (column: string) -> table.Rows.Find([|age|]).[column]
//Usage
vlookup "0~15" "Protection" |> printfn "%A"
There's no lack of CSV readers out there. I used this especially fast one (also available on NuGet).