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Python Dates and Times in Python (2014) Let's Build a Timed Quiz App Harder Time Machine

Zachary Maldonado
Zachary Maldonado
5,895 Points
Posted by Zachary Maldonado
Zachary Maldonado
5,895 Points

How do I convert a string argument into a keyword?

I believe the rest of code is correct and the part that's messing me up is that on timedelta() function I pass in a string instead of keyword for the first argument(cause thats what the time_machine function takes). Its probably something really simple that I have to do, but I just cant figure it out. Please help

time_machine.py 
import datetime

starter = datetime.datetime(2015, 10, 21, 16, 29)

# Remember, you can't set "years" on a timedelta!
# Consider a year to be 365 days.

## Example
# time_machine(5, "minutes") => datetime(2015, 10, 21, 16, 34)

def time_machine(integer, increment):
    new_time = starter + datetime.timedelta(increment = integer)
    return new_time

time_machine(5, "hours")

2 Answers

Brent Liang
PLUS
Brent Liang
Courses Plus Student 2,944 Points
Brent Liang
Brent Liang
Courses Plus Student 2,944 Points

Hey Zach,

I was having the exact same problem. What I did was having a nested if statement with multiple elifs to cover each scenario - apparently string argument can't be used for keyword in timedelta.

I've attached my code below, hope it offers some inspiration! 

import datetime

starter = datetime.datetime(2015, 10, 21, 16, 29)

# Remember, you can't set "years" on a timedelta!
# Consider a year to be 365 days.
def time_machine (num, type1):
    if type1 in ["minutes", "hours", "days"]:
        if type1 == "minutes":
            endtime = starter + datetime.timedelta (minutes = num)
            return endtime
        elif type1 == "hours":
            endtime = starter + datetime.timedelta (hours = num)
            return endtime
        elif type1 == "days":
            endtime = starter + datetime.timedelta (days = num)
            return endtime
    elif type1 == "years":
        endtime = starter + datetime.timedelta (days = 365*num)
        return endtime
    else:
        print("Invalid!")

## Example
# time_machine(5, "minutes") => datetime(2015, 10, 21, 16, 34)
```python
Zachary Maldonado
Zachary Maldonado
5,895 Points
Zachary Maldonado
Zachary Maldonado
5,895 Points

Thanks a lot Brent. I was having a tough time with this one. The string to keyword problem is something I'm gonna have to look more into. I couldn't seem to get it using dictionaries like Ryan had suggested. Happy coding!

Ryan S
Ryan S
27,276 Points
Ryan S
Ryan S
27,276 Points

Hi Zachary,

You don't need to call the function at the end. The challenge does this for you and will pass in whatever values it wants in order to test your code.

The other thing is that you can't substitute keyword names with variables. For example, in datetime.timedelta(), there are the keywords "hours", "minutes", "days", etc... Unfortunately you cannot set increment = "hours" then increment = integer. Although it seems to make sense, it doesn't actually work.

However, there is a way to do this by creating a dictionary of 'increment' and 'integer' and then unpacking it in timedelta. Or you can simply use if statements to handle each case.

Good luck