Using R with Dandelion

[Giorgio Alfredo Spedicato]

Hi all,

thank you for your great products. Is it possible for you to post some code snippets that show how to call your APIs directly within CRAN R code?

It would be very very useful...

[sam...@spaziodati.eu]

Hi Giorgio,
try with this:
https://gist.github.com/nicolasambin/083a237dc8eb438188b1

I've simply use "RCurl" to make a request to dataTXT fed with the right parameters.
It doesn't handle requests exceptions. It allows you to input either a url or a string besides tuning other dataTXT parameters. It outputs a nice data.frame.

Let us now whether there are problems and feel free to share with us your impressions and results. We're always looking for improving our service.

Nicola

[Giorgio Spedicato]

I'm sorry but I tried to use your API and I got this error:

library("jsonlite")

library("RCurl")

# the following function picks as parameters:

# either a text or a url

# app_id

# app_key

# include (a list of comma separated fields (you may insert: image,abstract,categories,types,lod))

# min_confidence (set by deafault to 0.6)

# language (set to automatic detection)

# social (which enables to parse hashtags etc. (set to false))

# it returns (unless no request errors (uncaught) occur) either a data.frame having as many rows as the annotations and 

# columns based on the include parameter or a message 'No entities found'

# it corresponds to the followings GET requests:

# https://api.dandelion.eu/datatxt/nex/v1/?(url|text)=input&$app_id=app_id&$app_key=app_key&include=include

# &min_confidence=min_confidence&lang=language&social=social

dataTxtNex <- function(input, app_id, app_key, include, min_confidence=.6, language='auto', social=F) {

  nex <- 'https://api.dandelion.eu/datatxt/nex/v1/'

  params <- list()

  params['$app_id'] <- app_id

  params['$app_key'] <- app_key

  if (grepl("^https?://", input)){

    params['url'] <- input

  } else {

    params['text'] <- input

  }

  params['min_confidence'] <- min_confidence

  params['social'] <- social

  params['include'] <- include

  params['lang'] <- language

  dataTxtReply <- fromJSON(getForm(nex, .params=params, .checkParams = TRUE))

  annotations <- dataTxtReply$annotations

  if (length(annotations) > 1) {

    return(annotations)

  } else {

    return('No entities found')

  }

}

ciao<-dataTxtNex(input = "Quest'anno ci saranno le elezioni del rettore. Speriamo che vinca la lista di Francesca.",

                 app_id="myappid",

                 app_key="myappkey",

                 include="categories")

Error in function (type, msg, asError = TRUE)  : 

  SSL certificate problem: self signed certificate in certificate chain.

 I used myappid and myappkey as shown in my dashboard

[sam...@spaziodati.eu]

That's seems to be an issue with SSL verification with getForm and, in general the RCurl library. (See, e.g., http://stackoverflow.com/questions/17411313/ssl-verification-causes-rcurl-and-httr-to-break-on-a-website-that-should-be-le)

I could not replicate the error, but I understood there are two possibilities:
- either setting ssl.verifypeer = FALSE in the RCurl options (but it is not a really good practice), i.e. replace:
getForm(nex, .params=params, .checkParams = TRUE)
with
getForm(nex, .params=params, .checkParams = TRUE, ssl.verifypeer = FALSE)

- or type
cert <- system.file("CurlSSL/cacert.pem", package = "RCurl")
and then add cainfo = cert to getForm, i.e. replace:
getForm(nex, .params=params, .checkParams = TRUE)
with
getForm(nex, .params=params, .checkParams = TRUE, cainfo = cert)

Tell us whether this fixed your problem.