Sort Json Data In List According To Timestamp

I am loading data(20 elements) to another file on load...here I want to sort these 20 elements according to timestamp I am using in list element. import json from collections

Solution 1:

Trivia:

Since you're using an OrderedDict - your records are already sorted by timestamp (to be honest - they're not, but recordses order is preserved).

The only unexpected behaviour with your code - when you "create" (overwrite) existed one student in line:

record[name] = {'Student ID:': p, 'Class:': a, 'Marks': n, 'time': time }

And if name in record: already - order is broken, so your idea about sorting isn't a meaningless, but I think, that it's better and more rational to just be sure of the recordses order, than sort records each time.

Workaround:

Square brackets after variable name means that this object is subscriptable (for e.g. tuple, list, dict, string and many more). Subscriptable means that this object at least implements the __getitem__() method (and __setitem__() in your case).

First method handles case, when you're trying to pull something from subscriptable object (by index/key/anything) and the second one - when you're trying to overwrite something.

And I suggest to implement such a feature with custom class:

classOrderedTimeDict(OrderedDict):
    def__setitem__(self, key, value):
        if key in self:
            # if key is already exist - move it to the end
            self.move_to_end(key)
        # standard behaviour
        OrderedDict.__setitem__(self, key, value)

and in your code just use this ordered dictionary instead of base ordered!

Conclusion:

Pros: No need to sort things, because we keep desired order.

Cons: If you're already has "unordered" data - you need to sort it once.

To sort ordered dict by time stamp you can use this function:

defsort_by_timestamp(dict):
    return OrderedDict(sorted(dict.items(), key=lambda get_time_stamp: get_time_stamp[1]['time']))

References:

• In Python, what does it mean if an object is subscriptable or not?
• OrderedDict Examples and Recipes