Added function 'search_images_ddg' to search Duck Duck Go with same a…

…pi as 'search_images_bing', except for the need for the api-key. Also, this function removes duplicated urls. Accordingly, the paramater is 'max_n' (fastai#250)

utils.py

@@ -40,6 +40,33 @@ def search_images_bing(key, term, min_sz=128, max_images=150):
 
 # -
 
+def search_images_ddg(key,max_n=200):
+     """Search for 'key' with DuckDuckGo and return a unique urls of 'max_n' images
+        (Adopted from https://github.com/deepanprabhu/duckduckgo-images-api)
+     """
+     url        = 'https://duckduckgo.com/'
+     params     = {'q':key}
+     res        = requests.post(url,data=params)
+     searchObj  = re.search(r'vqd=([\d-]+)\&',res.text)
+     if not searchObj: print('Token Parsing Failed !'); return
+     requestUrl = url + 'i.js'
+     headers    = {'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:71.0) Gecko/20100101 Firefox/71.0'}
+     params     = (('l','us-en'),('o','json'),('q',key),('vqd',searchObj.group(1)),('f',',,,'),('p','1'),('v7exp','a'))
+     urls       = []
+     while True:
+         try:
+             res  = requests.get(requestUrl,headers=headers,params=params)
+             data = json.loads(res.text)
+             for obj in data['results']:
+                 urls.append(obj['image'])
+                 max_n = max_n - 1
+                 if max_n < 1: return L(set(urls))     # dedupe
+             if 'next' not in data: return L(set(urls))
+             requestUrl = url + data['next']
+         except:
+             pass
+
+
 def plot_function(f, tx=None, ty=None, title=None, min=-2, max=2, figsize=(6,4)):
     x = torch.linspace(min,max)
     fig,ax = plt.subplots(figsize=figsize)