I have a huge file (with around 200k inputs). The inputs are in the form: A B C D B E F C A B D D I am reading this file and storing it in a list as follows: text = f.read().split('\n') This splits the file whenever it sees a new line. Hence text is like follows: [[A B C D] [B E F] [C A B D] [D]] I have to now store these values in a dictionary where the key values are the first element from each list. i.e the keys will be A, B, C, D. I am finding it difficult to enter the values as the remaining elements of the list. i.e the dictionary should look like: {A: B C D; B: E F; C: A B D; D: 0} I have done the following: inlinkDict = {} for doc in text: adoc= doc.split(' ') docid = adoc[0] inlinkDict[docid] = inlinkDict.get(docid,0) + {I do not understand what to put in here} Please help as to how should i add the values to my dictionary. It should be 0 if there are no elements in the list except for the one which will be the key value. Like in example for 0.