python代写: Level 5: Advanced Python Syntax

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Exercises

Level 5: Advanced Python Syntax

5.1: Date/Time

  1. 1)  Create a program that does the following:
    1. Asks the user to input year, month, day, hour, minute, second, microsecond (one after

      another).

    2. Create a datetime variable with the entered info.
    3. Extract the datetime into year, month, day, hour, minutes, second, and microsecond.

      Display the following result (where … is the extracted value):

      Year: …
      Month: …
      Day: …
      Hour: … Minute: … Second: … Microsecond: …

    4. Display the entered datetime with the following format: 2016-09-25 18:23:14:12342
    5. Display the entered datetime with the following format: 2016 September 25

      06:24:14:12342 PM

    6. Do parts d-e with the current local time.
    7. Do parts d-e with the current UTC time.
  2. 2)  Modify the above program to request the user enter the date in the following format (for example): 2016-09-25 18:23:14:12342
  3. 3)  Modify the above program to request the user enter the date in the following format (for example): 2016 September 25 06:24:14:12342 PM
  4. 4)  Create a ‘date calculator’ program. It should do the following:
    1. Prompt the user to enter any date and time.
    2. Prompt the user to enter a delta time that is used to add or subtract from the original. For

      example, if the user enters -00:25:13:0 then subtract 25 minutes and 13 seconds (and zero microseconds). Another example: 72:12:00:154 means to add 72 hours, 12 minutes, and 154 microseconds.

    3. Display the calculated resulting date and time, in an easily-readable format.
  1. 5)  Create a ‘date differential’ program. It should do the following:
    1. Prompt the user to enter any date and time.
    2. Prompt the user to enter another date and time.
    3. Subtract the two datetimes and display the result to the user. It should be displayed in

      several separate ways:

      1. Total number of days (including fractions of days).
      2. Total number of hours (including fractions).
      3. Total number of minutes (including fractions).
      4. Total number of seconds (including fractions).
      5. Total number of microseconds (including fractions).
      6. A complete (grammatically-correct) sentence that breaks everything down to the

        correct units and excluding any 0s. For example:

        The difference is 5 days, 3 hours, 16 minutes, 10 seconds, and 150 microseconds.

  2. 6)  Modify your Loan classes to take a loan start date and loan end (maturity) date instead of a term parameter. Create a term method that calculates and returns the loan term (in months) from the two dates.

Decorators

5.2: Decorators

1) Modify the Timer class to work as a decorator (feel free to use the provided sample code). Its usage should look like this:

An example output would look like: <function myFunc at 0x34173DF0>: 1.5467 seconds How does this compare to the previous approach to using the context manager? When is this

more useful and when are context managers more useful?

Memoization

  1. 2)  Create a decorator that memoize’s the result of a function. This decorator should be flexible enough that it can work with a function with any number of parameters. Note that memoizing should happen on a per-parameter basis; meaning, cache the result for every unique set of parameter values. Hint: Use a dict.

    Be sure to test this decorator on different functions to ensure it works properly. You should also use in conjunction with the timer decorator, to demonstrate that subsequent calls to the memoized function are quicker than the initial call for a given parameter set.

  2. 3)  Use your memoization decorator from the previous exercise to memoize the recursive versions of the Loan waterfall functions. Time the functions before and after; do you see a difference?

In practice, there are quite a few considerations when implementing a memoization decorator. For example, there are memory considerations (what happens to the cache if/when an object or function gets destroyed?). However, all of this is beyond the scope of this course. Note that many firms will have internal libraries that already have a memoization decorator or class implemented, for you to use out-of-the-box.

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