Added --citations-only option. It prints all the articles that cite the queried one

scholar.py

@@ -166,6 +166,7 @@
 import re
 import sys
 import warnings
+import time
 
 try:
     # Try importing for Python 3
@@ -879,7 +880,7 @@ class ScholarSettings(object):
 
     def __init__(self):
         self.citform = 0 # Citation format, default none
-        self.per_page_results = None
+        self.per_page_results = 10
         self._is_configured = False
 
     def set_citation_format(self, citform):
@@ -893,8 +894,7 @@ def set_citation_format(self, citform):
     def set_per_page_results(self, per_page_results):
         self.per_page_results = ScholarUtils.ensure_int(
             per_page_results, 'page results must be integer')
-        self.per_page_results = min(
-            self.per_page_results, ScholarConf.MAX_PAGE_RESULTS)
+        self.per_page_results = min(self.per_page_results, ScholarConf.MAX_PAGE_RESULTS)
         self._is_configured = True
 
     def is_configured(self):
@@ -1026,6 +1026,38 @@ def send_query(self, query):
 
         self.parse(html)
 
+    def get_citations(self,query):
+        """
+        Given a query, it retrieve the list of articles that cite the first 
+        article returned by the query.
+        It's done in two steps: first it retrieves the citations url of the 
+        first article, then it retrieves the articles that cite it
+        """
+        self.send_query(query)
+
+        if len(self.articles)==0 or self.articles[0]['url_citations'] is None:
+            return 
+        citations_url=self.articles[0]['url_citations']
+        citations_num=self.articles[0]['num_citations']
+        self.clear_articles()
+
+        html = self._get_http_response(url=citations_url,
+                                       log_msg='dump of query response HTML',
+                                       err_msg='results retrieval failed')
+        if html is None:
+            return
+        self.parse(html)
+        while len(self.articles)<citations_num:
+            # this is a workaround to fetch all the citations, ought to be better integrated at some point
+            time.sleep(1)
+            html = self._get_http_response(url=citations_url+'&start='+str(len(self.articles)),
+                                           log_msg='dump of query response HTML',
+                                           err_msg='results retrieval failed')
+            if html is None:
+                return
+
+            self.parse(html)
+
     def get_citation_data(self, article):
         """
         Given an article, retrieves citation link. Note, this requires that
@@ -1043,7 +1075,6 @@ def get_citation_data(self, article):
                                        err_msg='requesting citation data failed')
         if data is None:
             return False
-
         article.set_citation_data(data)
         return True
 
@@ -1187,6 +1218,8 @@ def main():
                      help='Do not include patents in results')
     group.add_option('--no-citations', action='store_true', default=False,
                      help='Do not include citations in results')
+    group.add_option('--citations-only', action='store_true', default=False,
+                     help='Prints only the citations list in results')
     group.add_option('-C', '--cluster-id', metavar='CLUSTER_ID', default=None,
                      help='Do not search, just use articles in given cluster ID')
     group.add_option('-c', '--count', type='int', default=None,
@@ -1290,7 +1323,11 @@ def main():
         options.count = min(options.count, ScholarConf.MAX_PAGE_RESULTS)
         query.set_num_page_results(options.count)
 
-    querier.send_query(query)
+
+    if options.citations_only:
+        querier.get_citations(query)
+    else:
+        querier.send_query(query)
 
     if options.csv:
         csv(querier)