arrgh (Pronunciation: /ɑː/ or /är/) is an interface to the OpenCPU R server system.

Overview

The arrgh package provides API interfaces to remote or local OpenCPU R servers.

Go is a well established network systems language and has seen increasing use in data science and other fields of scientific software development. The arrgh package allows developers to leverage the rich statistical analysis environment available through R that is lacking in the Go ecosystem.

Example

``` package main

import ( "bufio" "encoding/json" "fmt" "io" "log" "net/url" "os" "path" "path/filepath" "strings" "time"

"github.com/kortschak/arrgh"

)

func main() { r, err := arrgh.NewRemoteSession("http://public.opencpu.org", "", 10*time.Second) if err != nil { log.Fatal(err) } defer r.Close()

// Send a query to get a session result for the linear
// regression: coef(lm(speed~dist, data=cars)).
resp, err := r.Post(
    "library/base/R/identity",
    "application/x-www-form-urlencoded",
    nil,
    strings.NewReader("x="+url.QueryEscape("coef(lm(speed ~ dist, data = cars))")),
)
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

// Get each part of the session result and display it,
// keeping the location of the linear regression.
sc := bufio.NewScanner(resp.Body)
var val string
for sc.Scan() {
    // API root path stripping here depends on consistency
    // between os.Separator and the URL path separator.
    p, err := filepath.Rel(r.Root(), sc.Text())
    if err != nil {
        log.Fatal(err)
    }
    if path.Base(p) == ".val" {
        val = p
    }
    fmt.Printf("%s:\n", p)

    resp, err := r.Get(p, nil)
    if err != nil {
        log.Fatal(err)
    }
    io.Copy(os.Stdout, resp.Body)
    fmt.Print("\n\n")
    resp.Body.Close()
}

// Get the linear regression result as JSON.
res, err := r.Get(path.Join(val, "json"), url.Values{"digits": []string{"10"}})
if err != nil {
    log.Fatal(err)
}
defer res.Body.Close()

// Decode the result into a [2]float64.
var lm [2]float64
dec := json.NewDecoder(res.Body)
err = dec.Decode(&lm)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("lm: intercept=%f dist=%f\n", lm[0], lm[1])

} ```

Output: ``` tmp/x0113a3ca85/R/identity: function (x) x

tmp/x0113a3ca85/R/.val: (Intercept) dist 8.2839056 0.1655676

tmp/x0113a3ca85/stdout: (Intercept) dist 8.2839056 0.1655676

tmp/x0113a3ca85/source: identity(x = coef(lm(speed ~ dist, data = cars)))

tmp/x0113a3ca85/console:

identity(x = coef(lm(speed ~ dist, data = cars))) (Intercept) dist 8.2839056 0.1655676

tmp/x0113a3ca85/info: R version 3.4.1 (2017-06-30) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu 16.04.2 LTS

Matrix products: default BLAS: /usr/lib/openblas-base/libblas.so.3 LAPACK: /usr/lib/libopenblasp-r0.2.18.so

locale: [1] LCCTYPE=enUS.UTF-8 LCNUMERIC=C LCTIME=enUS.UTF-8
[4] LCCOLLATE=enUS.UTF-8 LCMONETARY=enUS.UTF-8 LCMESSAGES=C
[7] LCPAPER=C LCNAME=C LCADDRESS=C
[10] LCTELEPHONE=C LCMEASUREMENT=C LCIDENTIFICATION=C

attached base packages: [1] stats graphics grDevices utils datasets methods base

other attached packages: [1] opencpu_2.0.3.1

loaded via a namespace (and not attached): [1] Rcpp0.12.11 lattice0.20-35 mime0.5 plyr1.8.4
[5] grid3.4.1 gtable0.2.0 sys1.4 jsonlite1.5
[9] unix1.3 magrittr1.5 scales0.4.1 evaluate0.10.2 [13] ggplot22.2.1 rlang0.1.1 stringi1.1.5 curl2.7
[17] lazyeval0.2.0 webutils0.6 tools3.4.1 stringr1.2.0
[21] munsell0.4.3 parallel3.4.1 sendmailR1.2-1 compiler3.4.1
[25] colorspace1.3-2 base64enc0.1-3 openssl0.9.6 tibble1.3.3

tmp/x0113a3ca85/files/DESCRIPTION: Package: x0113a3ca85 Type: Session Version: 2.0.3.1 Author: OpenCPU Date: 2017-07-07 Description: This file is automatically generated by OpenCPU.

lm: intercept=8.283906 dist=0.165568 ```

Installation

arrgh requires a Go installation, and if using a local R instance OpenCPU (tested on v1.6 and v2.0) and semver must be installed as R packages.

go get github.com/kortschak/arrgh

See the OpenCPU CRAN page for a complete description of OpenCPU R and system dependencies and this page for instructions for installing OpenCPU from source.

Documentation

http://godoc.org/github.com/kortschak/arrgh

Getting help

Help or similar requests can be asked on the bug tracker, or for more general OpenCPU questions at the OpenCPU google groups.

https://groups.google.com/forum/#!forum/opencpu

Contributing

If you find any bugs, feel free to file an issue on the github issue tracker. Pull requests are welcome.

Citing

If you use the arrgh package, please cite:

Kortschak, R Daniel (2018). arrgh: a Go interface to the OpenCPU R server system. Journal of Open Source Software, 3(21), 517, https://doi.org/10.21105/joss.00517

License

arrgh is distributed under a modified BSD license.