Add SPARQL notebooks

lod/helpers.py

@@ -0,0 +1,94 @@
+from IPython.core.magic import (register_line_magic, register_cell_magic,
+                                register_line_cell_magic)
+
+from IPython.display import HTML, display, Image
+from urllib.request import Request, urlopen
+from urllib.parse import quote_plus, urlencode
+from urllib.error import HTTPError
+
+import json
+
+
+def send_query(query, endpoint):
+    FORMATS = ",".join(["application/sparql-results+json", "text/javascript", "application/json"])
+
+    data = {'query': query}
+    # b = quote_plus(query)
+
+    r = Request(endpoint,
+                data=urlencode(data).encode('utf-8'),
+                headers={'content-type': 'application/x-www-form-urlencoded',
+                         'accept': FORMATS},
+                method='POST')
+    return json.loads(urlopen(r).read().decode('utf-8'));
+
+
+def tabulate(tuples, header=None):
+    if not header:
+        header, tuples = tuples[0], tuples[1:]
+    header = '<tr>{}<tr>'.format(''.join('<th>{}</th>'.format(h) for h in header))
+    rows = []
+    for row in tuples:
+        inner = ''.join('<td>{}</td>'.format(c) for c in row)
+        rows.append('<tr>{}</tr>'.format(inner))
+    body = ''.join(rows)
+    table = '<table><thead>{header}</thead><tbody>{body}</tbody></table>'.format(body=body,
+                                                                                 header=header)
+    return table
+
+
+LAST_QUERY = {}
+
+
+def query(query, endpoint=None, print_table=False):
+    global LAST_QUERY
+
+    endpoint = endpoint or "http://dbpedia.org/sparql"
+    results = send_query(query, endpoint)
+    tuples = to_table(results)
+
+
+    columns = {}
+    header, values = tuples[0], tuples[1:]
+
+    for ix, h in enumerate(header):
+        columns[h] = []
+        for row in values:
+            columns[h].append(row[ix])
+
+    LAST_QUERY.update({
+        'query': query,
+        'endpoint': query,
+        'results': results,
+        'tuples': values,
+        'columns': columns
+    })
+
+    if not print_table:
+        return tuples
+    return HTML(tabulate(tuples))
+
+
+def to_table(results):
+    table = []
+    header = results['head']['vars']
+    table.append(header)
+    for result in results["results"]["bindings"]:
+        table.append(tuple(result.get(h, {}).get('value', "") for h in header))
+    return table
+
+
+@register_cell_magic
+def sparql(line, cell):
+    try:
+        return query(cell, endpoint=line, print_table=True)
+    except HTTPError as ex:
+        error_message = ex.read().decode('utf-8')
+        print('Error {}. Reason: {}'.format(ex.status, ex.reason))
+        print(error_message)
+
+
+def show_photos(values):
+    for value in values:
+        if 'http://' in value:
+            display(Image(url=value))