Lists + Empty Lists

[Axel_Erfurt]

days = ['Monday','Tuesday', 'Wednesday', 'Thursday','Friday', 'Saturday', 'Sunday']
weekdays = []
weekends = []

print("weekdays:")
for x in range(5):
    print(days[x])
    weekdays.append(days[x])

print("\nweekend:")
for x in range(5, len(days)):
    print(days[x])
    weekends.append(days[x])

shorter

days = ['Monday','Tuesday', 'Wednesday', 'Thursday','Friday', 'Saturday', 'Sunday']
weekdays = days[:5]
weekends = days[5:]

print("weekdays:") 
print("\n".join(weekdays))
print("\nweekends:")
print("\n".join(weekends))

result on both

Output:
weekdays:
Monday
Tuesday
Wednesday
Thursday
Friday

weekends:
Saturday
Sunday

[deanhystad]

What Axel_Erfurt is doing is called slices, and it is how you should extract "slices" from a list. A slice is like this: the_list[start:end]. The slice starts with the_list[start] and ends at the_list[end-1].

If you leave out the start, i.e. the_list[:end], the slice includes all values starting with the_list[0] and ending with the_list[end-1]. If you leave out the end, i.e. the_list[start:], the slice includes all values starting at the_list[start] and ending at the end of the list.

It is a common belief among new Python programmers that print() can do things like return values or assign values. This is about as incorrect as you can be. All print(str) does is write str to a stream called stdout (standard output). Usually this appears in the terminal where you launched the Python program, but it can be redirected to appear in a different window or a file or a pipe.

print(days) does not add anything to a list or remove anything from a list. print(days) doesn't even write days to stdout. It writes a string what some programmer thought fairly represents days.

If you wanted to use a list to copy values from days to weekdays it would look something like this:

weekdays = []
weekends = []
for i in range(5):
    weekdays.append(day[i])
for i in range(5, 7):
    weekends.append(day[i])

Just looking at how ugly this code is, it is easy to understand why slices were added to the language.

[Pytho13]

What Axel_Erfurt is doing is called slices, and it is how you should extract "slices" from a list. A slice is like this: the_list[start:end]. The slice starts with the_list[start] and ends at the_list[end-1].

If you leave out the start, i.e. the_list[:end], the slice includes all values starting with the_list[0] and ending with the_list[end-1]. If you leave out the end, i.e. the_list[start:], the slice includes all values starting at the_list[start] and ending at the end of the list.

It is a common belief among new Python programmers that print() can do things like return values or assign values. This is about as incorrect as you can be. All print(str) does is write str to a stream called stdout (standard output). Usually this appears in the terminal where you launched the Python program, but it can be redirected to appear in a different window or a file or a pipe.

print(days) does not add anything to a list or remove anything from a list. print(days) doesn't even write days to stdout. It writes a string what some programmer thought fairly represents days.

If you wanted to use a list to copy values from days to weekdays it would look something like this:

weekdays = []
weekends = []
for i in range(5):
    weekdays.append(day[i])
for i in range(5, 7):
    weekends.append(day[i])

Just looking at how ugly this code is, it is easy to understand why slices were added to the language.

Hi, thank you so much for explaining this. You are right, I'm new to python and finding parts tricky to understand. I was of the impression the I would need to assign from one list to the other two and this is what I was typing into Google for assistance so I really appreciate you taking the time to explain this.

Have a great day :)

[snippsat]

Would I be right in thinking that I would need to print number 0-4 and assign them to the first empty list and then assign the 5-6 to the second empty list?

It's how to assign it that I'm mainly having trouble with.

Can write some code where look at enumerate days and making a dictionary.

>>> days = ['Monday','Tuesday', 'Wednesday', 'Thursday','Friday', 'Saturday', 'Sunday']
>>> week = {}
>>> for index, day in enumerate(days, 1):
...     week[index] = day  
...     
>>> week
{1: 'Monday',
 2: 'Tuesday',
 3: 'Wednesday',
 4: 'Thursday',
 5: 'Friday',
 6: 'Saturday',
 7: 'Sunday'}
>>> week[6]
'Saturday'

Look at slicing out when it's a dictionary.

>>> weekends_day  = {6, 7}
>>> {key:week[key] for key in weekends_day if key in week}
{6: 'Saturday', 7: 'Sunday'}

Or using itertools.islice which is clean way to set from to end day.

>>> import itertools
>>> 
>>> weekdays = dict(itertools.islice(week.items(), 0, 5))
>>> weekends = dict(itertools.islice(week.items(), 5, 7))
>>> 
>>> weekdays
{1: 'Monday', 2: 'Tuesday', 3: 'Wednesday', 4: 'Thursday', 5: 'Friday'}
>>> weekends
{6: 'Saturday', 7: 'Sunday'}

[Larz60+]

Can write some code where look at enumerate days and making a dictionary.

suggested top one in post 7

[pythonprogrammer1101935]

Hello Pytho13!! ,

I hope you are well. I know how to solve this problem!

Make a for loop, with the i starting from 1 and ending to 4. Code: for i in range(5):
And inside the loop, put days[i] into weekdays. If you don't understand what I mean,
I mean like when the i value is zero you put the 1st item of "days"(Monday) into the list "weekdays".
By the way here is the code to do that:
for i in range(5):
weekdays.append(days[i])
It will go on until it reaches Saturday.
Now for the next list "weekends".
Make another for loop with i starting from 5 to 6 because days[5] and days[6] are the weekend days.
Code for the for loop: for i in range(5, 7, 1):
Next you need to actually put the weekdays into the "weekends" list.
Now that you have got your for loop, we need to put something inside it!
It's pretty much the same code last time except a little different.
The i starts at 5, and days[5] is Saturday. We need to put Saturday into the "weekends" list.
And the i ends at 6, and days[6] is Sunday. We also need to put Sunday into the "weekends" list.
So the code we need to put inside this for loop is:
weekends.append(days[i])
When the for loop starts, the i will be 5. weekends.append(days[5]) that code will append Saturday into the "weekends" list. When the for loop ends, the i will be 6. weekends.append(days[6]) that code will append Sunday into the "weekends" list.
Hope I was able to solve the problem for you! Sorry this was a long message, I was just trying to explain the easiest I could. If you need any more help on anything please contact me! Have a great day.