CODEWITHSUNDEEP
chartsplotf#
Klark
Klark

Reputation: 8280

F# plotting datetime issues

I have a collection that is in format datetimeoffset - option int64. I would like to plot a line from this data.

I tried with with just piping my data to Chart.Line:

Chart.Line(data |> Seq.map (fun r -> r.time.DateTime, r.input.Value)) but i got following output.

enter image description here

Now I know my data doesn't look like this. At least I tried running:

data |> Array.map (fun r -> r.Timestamp.DateTime) |> Array.min
data |> Array.map (fun r -> r.Timestamp.DateTime) |> Array.max

And got

DateTime = 10/29/2014 6:30:15 PM
DateTime = 10/30/2014 6:00:15 PM

So I don't have any data near the beginning of the previous century.

When I plot by DateTime.Ticks instead of datetime data looks as it should be looking:

enter image description here

Any idea what is going on here?

Upvotes: 1

Views: 190

Answers (1)

Tomas Petricek
Tomas Petricek

Reputation: 243096

Based on the screenshot, I suppose you're using the F# Charting library.

I did a quick test using the latest version and it seems to be handling DateTimeOffset correctly as the key, but DateTime incorrectly! Given the following setup:

#load "packages/FSharp.Charting.0.90.7/FSharp.Charting.fsx"
open FSharp.Charting
open System

The following works fine:

[ for i in 0 .. 100 do 
    yield DateTimeOffset(DateTime.Now.AddHours(float i)), int64 i ]
|> Chart.Line

But the following behaves similarly to your snippet:

[ for i in 0 .. 100 do 
    yield DateTime.Now.AddHours(float i), int64 i ]
|> Chart.Line

So the workaround for you should be to just return r.time rather than getting DateTime:

Chart.Line(data |> Seq.map (fun r -> r.time, r.input.Value))

This seems to be a bug! Please submit an issue on the project GitHub page.

EDIT Figured it out - there is a difference between how DateTime and DateTimeOffset behave.

Upvotes: 1

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