from functools import reduce
def values_incremented(some_data):
    return [{'value': current_sum, 'date': element['date']} for element,
        current_sum in zip(some_data, reduce(lambda x, y: [y['value']] if 
        not x else x + [x[-1] + y['value']], some_data, []))]
Python compute running sum of values in one-line