Academic Search API

CalcHistogram

The calchistogram REST API is used to calculate the distribution of attribute values for a set of paper entities.

Try it

Request URL

Request parameters

string

A query expression that specifies the entities over which to calculate histograms.

(optional)
string

Name of the model that you wish to query. Currently, the value defaults to "latest".

(optional)
string

A comma delimited list that specifies the attribute values that are included in the response. Attribute names are case-sensitive.

(optional)
number

Number of results to return.

(optional)
number

Index of the first result to return.

Request headers

string
Subscription key which provides access to this API. Found in your Cognitive Services accounts.

Request body

Response 200

Response (JSON)

 
NameDescription
expr The expr parameter from the request.
num_entities Total number of matching entities.
histograms An array of histograms, one for each attribute specified in the request.
histograms[x].attribute Name of the attribute over which the histogram was computed.
histograms[x].distinct_values Number of distinct values among matching entities for this attribute.
histograms[x].total_count Total number of value instances among matching entities for this attribute.
histograms[x].histogram Histogram data for this attribute.
histograms[x].histogram[y].value A value for the attribute.
histograms[x].histogram[y].prob Total probability of matching entities with this attribute value.
histograms[x].histogram[y].count Number of matching entities with this attribute value.
aborted True if the request timed out.
 

{
  "expr": "And(Composite(AA.AuN=='jaime teevan'),Y>2012)",
  "num_entities": 37,
  "histograms": [
    {
      "attribute": "Y",
      "distinct_values": 3,
      "total_count": 37,
      "histogram": [
        {
          "value": 2014,
          "prob": 1.275e-07,
          "count": 15
        },
        {
          "value": 2013,
          "prob": 1.184e-07,
          "count": 12
        },
        {
          "value": 2015,
          "prob": 8.279e-08,
          "count": 10
        }
      ]
    },
    {
      "attribute": "F.FN",
      "distinct_values": 34,
      "total_count": 53,
      "histogram": [
        {
          "value": "crowdsourcing",
          "prob": 7.218e-08,
          "count": 9
        },
        {
          "value": "information retrieval",
          "prob": 4.082e-08,
          "count": 4
        },
        {
          "value": "personalization",
          "prob": 2.384e-08,
          "count": 3
        },
        {
          "value": "mobile search",
          "prob": 2.119e-08,
          "count": 2
        }
      ]
    }
  ]
}

Response 400

{ "error": { "code": "Bad Argument", "message": "The parameter is missing." } }

Response 401

{"error":{"code":"Unspecified","message":"Access denied due to invalid subscription key. Make sure you are subscribed to an API you are trying to call and provide the right key."}}

Response 500

{ "error": { "code": "Unspecified", "message": "Internal server error." } }

Response 404

{ "error": { "code": "Unspecified", "message": "The requested resource is not found." } }

Response 403

{ "error": { "code": "QuotaExceeded", "message": "Out of call volume quota. Quota will be replenished later." } }

Code samples

@ECHO OFF

curl -v -X GET "https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram?expr={string}&model=latest&attributes={string}&count=10&offset=0"
-H "Ocp-Apim-Subscription-Key: {subscription key}"

--data-ascii "{body}" 
using System;
using System.Net.Http.Headers;
using System.Text;
using System.Net.Http;
using System.Web;

namespace CSHttpClientSample
{
    static class Program
    {
        static void Main()
        {
            MakeRequest();
            Console.WriteLine("Hit ENTER to exit...");
            Console.ReadLine();
        }
        
        static async void MakeRequest()
        {
            var client = new HttpClient();
            var queryString = HttpUtility.ParseQueryString(string.Empty);

            // Request headers
            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "{subscription key}");

            // Request parameters
            queryString["expr"] = "{string}";
            queryString["model"] = "latest";
            queryString["attributes"] = "{string}";
            queryString["count"] = "10";
            queryString["offset"] = "0";
            var uri = "https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram?" + queryString;

            var response = await client.GetAsync(uri);
        }
    }
}	
// // This sample uses the Apache HTTP client from HTTP Components (http://hc.apache.org/httpcomponents-client-ga/)
import java.net.URI;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class JavaSample 
{
    public static void main(String[] args) 
    {
        HttpClient httpclient = HttpClients.createDefault();

        try
        {
            URIBuilder builder = new URIBuilder("https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram");

            builder.setParameter("expr", "{string}");
            builder.setParameter("model", "latest");
            builder.setParameter("attributes", "{string}");
            builder.setParameter("count", "10");
            builder.setParameter("offset", "0");

            URI uri = builder.build();
            HttpGet request = new HttpGet(uri);
            request.setHeader("Ocp-Apim-Subscription-Key", "{subscription key}");


            // Request body
            StringEntity reqEntity = new StringEntity("{body}");
            request.setEntity(reqEntity);

            HttpResponse response = httpclient.execute(request);
            HttpEntity entity = response.getEntity();

            if (entity != null) 
            {
                System.out.println(EntityUtils.toString(entity));
            }
        }
        catch (Exception e)
        {
            System.out.println(e.getMessage());
        }
    }
}

<!DOCTYPE html>
<html>
<head>
    <title>JSSample</title>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
</head>
<body>

<script type="text/javascript">
    $(function() {
        var params = {
            // Request parameters
            "expr": "{string}",
            "model": "latest",
            "attributes": "{string}",
            "count": "10",
            "offset": "0",
        };
      
        $.ajax({
            url: "https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram?" + $.param(params),
            beforeSend: function(xhrObj){
                // Request headers
                xhrObj.setRequestHeader("Ocp-Apim-Subscription-Key","{subscription key}");
            },
            type: "GET",
            // Request body
            data: "{body}",
        })
        .done(function(data) {
            alert("success");
        })
        .fail(function() {
            alert("error");
        });
    });
</script>
</body>
</html>
#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    
    NSString* path = @"https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram";
    NSArray* array = @[
                         // Request parameters
                         @"entities=true",
                         @"expr={string}",
                         @"model=latest",
                         @"attributes={string}",
                         @"count=10",
                         @"offset=0",
                      ];
    
    NSString* string = [array componentsJoinedByString:@"&"];
    path = [path stringByAppendingFormat:@"?%@", string];

    NSLog(@"%@", path);

    NSMutableURLRequest* _request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:path]];
    [_request setHTTPMethod:@"GET"];
    // Request headers
    [_request setValue:@"{subscription key}" forHTTPHeaderField:@"Ocp-Apim-Subscription-Key"];
    // Request body
    [_request setHTTPBody:[@"{body}" dataUsingEncoding:NSUTF8StringEncoding]];
    
    NSURLResponse *response = nil;
    NSError *error = nil;
    NSData* _connectionData = [NSURLConnection sendSynchronousRequest:_request returningResponse:&response error:&error];

    if (nil != error)
    {
        NSLog(@"Error: %@", error);
    }
    else
    {
        NSError* error = nil;
        NSMutableDictionary* json = nil;
        NSString* dataString = [[NSString alloc] initWithData:_connectionData encoding:NSUTF8StringEncoding];
        NSLog(@"%@", dataString);
        
        if (nil != _connectionData)
        {
            json = [NSJSONSerialization JSONObjectWithData:_connectionData options:NSJSONReadingMutableContainers error:&error];
        }
        
        if (error || !json)
        {
            NSLog(@"Could not parse loaded json with error:%@", error);
        }
        
        NSLog(@"%@", json);
        _connectionData = nil;
    }
    
    [pool drain];

    return 0;
}
<?php
// This sample uses the Apache HTTP client from HTTP Components (http://hc.apache.org/httpcomponents-client-ga/)
require_once 'HTTP/Request2.php';

$request = new Http_Request2('https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram');
$url = $request->getUrl();

$headers = array(
    // Request headers
    'Ocp-Apim-Subscription-Key' => '{subscription key}',
);

$request->setHeader($headers);

$parameters = array(
    // Request parameters
    'expr' => '{string}',
    'model' => 'latest',
    'attributes' => '{string}',
    'count' => '10',
    'offset' => '0',
);

$url->setQueryVariables($parameters);

$request->setMethod(HTTP_Request2::METHOD_GET);

// Request body
$request->setBody("{body}");

try
{
    $response = $request->send();
    echo $response->getBody();
}
catch (HttpException $ex)
{
    echo $ex;
}

?>
########### Python 2.7 #############
import httplib, urllib, base64

headers = {
    # Request headers
    'Ocp-Apim-Subscription-Key': '{subscription key}',
}

params = urllib.urlencode({
    # Request parameters
    'expr': '{string}',
    'model': 'latest',
    'attributes': '{string}',
    'count': '10',
    'offset': '0',
})

try:
    conn = httplib.HTTPSConnection('westus.api.cognitive.microsoft.com')
    conn.request("GET", "/academic/v1.0/calchistogram?%s" % params, "{body}", headers)
    response = conn.getresponse()
    data = response.read()
    print(data)
    conn.close()
except Exception as e:
    print("[Errno {0}] {1}".format(e.errno, e.strerror))

####################################

########### Python 3.2 #############
import http.client, urllib.request, urllib.parse, urllib.error, base64

headers = {
    # Request headers
    'Ocp-Apim-Subscription-Key': '{subscription key}',
}

params = urllib.parse.urlencode({
    # Request parameters
    'expr': '{string}',
    'model': 'latest',
    'attributes': '{string}',
    'count': '10',
    'offset': '0',
})

try:
    conn = http.client.HTTPSConnection('westus.api.cognitive.microsoft.com')
    conn.request("GET", "/academic/v1.0/calchistogram?%s" % params, "{body}", headers)
    response = conn.getresponse()
    data = response.read()
    print(data)
    conn.close()
except Exception as e:
    print("[Errno {0}] {1}".format(e.errno, e.strerror))

####################################
require 'net/http'

uri = URI('https://westus.api.cognitive.microsoft.com/academic/v1.0/calchistogram')
uri.query = URI.encode_www_form({
    # Request parameters
    'expr' => '{string}',
    'model' => 'latest',
    'attributes' => '{string}',
    'count' => '10',
    'offset' => '0'
})

request = Net::HTTP::Get.new(uri.request_uri)
# Request headers
request['Ocp-Apim-Subscription-Key'] = '{subscription key}'
# Request body
request.body = "{body}"

response = Net::HTTP.start(uri.host, uri.port, :use_ssl => uri.scheme == 'https') do |http|
    http.request(request)
end

puts response.body