triangle numbers

[Woody_MC_2022]

Hi all, I want to print the output as below:-

Output:
1
X2
XX3
XXX4
XXXX5
XXX4
XX3
X2
1

---

I tried to solve the problem above as below:-

line = '12345'
for i in range(1,6):
    print(line[-i:])
for i in range(1,6):
     print(line[i:])

output:

Output:
5
45
345
2345
12345
2345
345
45
5

how it works in crop what I want? can anyone help?

Yoriz write Sep-24-2022, 09:54 AM:
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[deanhystad]

The term is "slice", not "crop". Your pyramid program is printing slices o line.

You should not have "magic numbers" in you code like 6. If you change line to "123456", you should not have to know that you must also change 6 to 7. The program should do that for you. Python has a function that returns the number of items in a list. Plus, I don't think you want to use 6. 6 doesn't produce the correct result.

line = 'ABCDE'
for i in range(1, len(line)):
    print(line[-i:])
for i in range(len(line)):
    print(line[i:])

Output:
E
DE
CDE
BCDE
ABCDE
BCDE
CDE
DE
E

If you only want to print 1 element should use indexing, not slicing. This prints elements starting from the end, working tot the start, and then back to the end.

line = 'ABCDE'
for i in range(1, len(line)):
    print(line[-i])
for i in range(len(line)):
    print(line[i])

Output:
E
D
C
B
A
B
C
D
E

How could this be modified to print elements beginning at the start, moving to the end, and then back to the start?

[Woody_MC_2022]

thanks for your help.
actually, I want to have the output like as below:-

1
• 2
••3
•••4
••••5
•••4
••3
•2
1

[deanhystad]

Are the dots meant to be spaces? That would explain why the list looked wrong in your original post. That is even easier.

for i in range(5):
    print(f"{spaces}{i+1}")
for i in range(4, 0, -1):
    print(f"{spaces}{i}")

Now figure how to make "spaces".

[Woody_MC_2022]

Are the dots meant to be spaces? That would explain why the list looked wrong in your original post. That is even easier.

for i in range(5):
    print(f"{spaces}{i+1}")
for i in range(4, 0, -1):
    print(f"{spaces}{i}")

Now figure how to make "spaces".

cool.
Yes. the dots are meant to be spaces.

tried to use the code, it shows NameError: name 'spaces' is not defined.
can you help?
what is the difference between {} and ()?

[deanhystad]

Replacing "spaces" is an exercise left to the reader. I would read about the str datatype and what methods it supports. I bet there is a method for padding a string to some width. I'd also do some research on f'string formatting. There is a way to set the width of a string when it is printed. Very useful for printing out tables and having the columns line up. There is also an operator that you can use on strings to make a longer string by concatenating a short string some multiple number of times.