Add a flatten option

README.md

@@ -62,6 +62,17 @@ keyword.extract('beep beep and foo bar and beep beep and beep beep and foo bar',
 
 Returns `['beep beep']`.
 
+#### Option: flatten
+
+Returns all occurrences of the ngram. Useful for passing data to Natural's
+TF-IDF function. Note: the original order is not maintained. Off by default.
+
+```js
+keyword.extract('beep beep and foo bar and beep beep and beep beep and foo bar', {flaten: true})
+```
+
+Returns `['beep beep', 'beep beep', 'beep beep', 'foo bar', 'foo bar']`.
+
 #### Option: html
 
 Extracts the keywords from html text elements. The default is false.

index.js

@@ -94,8 +94,23 @@ exports.extract = function(text, options){
     });
   }
 
-  // Return results with scores or without depending on options
-  combined =  options.score ? combined : _.pluck(combined, 'term');
+  if (options.flatten){
+    // Flatten the results so that there is a list item for every occurence of
+    // the term
+    combined = _.flatten(
+      _.map(combined, function(result){
+        var flattened = [];
+        for (var i=0; i < result.tf; i++){
+          flattened.push(result.term);
+        }
+        return flattened;
+      })
+    );
+  }else{
+    // Return results with scores or without depending on options
+    combined =  options.score ? combined : _.pluck(combined, 'term');
+  }
+
 
   // Limit the results
   if (options.limit){