NOTE: the latest version is 1.0.3

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LTTB

Largest-Triangle-Three-Buckets Algorithm

Downsampling data for plotting

type alias Input a =
    { data : List a
    , threshold : Int
    , xGetter : a -> Float
    , yGetter : a -> Float
    }

downsample : Input a -> List a

Say we have a list of ten thousand of these:

type alias OurRecord =
    { id : Int
    , time : Time.Posix
    , temperature : Float
    , humidity : Float
    , comment : String
    }

and we just want five hundred when plotting time on the x-axis and temperature on the y-axis, then we can downsample it with:

LTTB.downsample
    { data = originalData
    , threshold = 500
    , xGetter = .time >> Time.posixToMillis >> toFloat
    , yGetter = .temperature
    }

which results in a List OurRecord of length 500 sorted by .time.

Modules

LTTB