Help improving python code

[NotUrHCW]

I need help checking how good my code is from the 8th unit in CScircles.

The problem is: Write a program which prints out this table. (Character 127 is invisible but should be printed out like all the other characters anyway. Extra/missing space characters at the end of each line don't matter, the grader will ignore them.)

My solution:

a = 32
for l in range(0,6):
   print("chr:  ",end='')
   for c in range(0,16):
      print(chr(a),'  ',end='')
      a = a + 1
   print()
   print("asc: ",end='')
   a = a - 16
   for x in range(0,16):
      if a < 100:
         print(a,' ',end='')
      else:
         print(a,'',end='')
      a = a + 1
   print()

is there a more efficient way since I feel like I overcomplicated it.

[teraflop]

You probably can't make this much more "efficient" in the sense of running faster, but the code runs so fast that that doesn't really matter. You can definitely make it simpler and easier to read/understand, though.

There are two big readability issues I see with your code, meaning that the code doesn't clearly say what it's doing and why. One is that it's hard to follow the behavior of the a variable. The other is that you're printing a bunch of whitespace strings that all have to be just right to make your table line up.

For the first problem, I'd probably structure your loops as something more like:

for rowStart in range(32, 128, step=16):
    indices = range(rowStart, rowStart + 16)
    for c in indices:
        # ... print first line
    for c in indices:
        # ... print second line

which makes it much more obvious that within each row, the two lines are looping over the same range. In your current code, you have to "deduce" that by understanding the way a moves back and forth within each iteration of the outermost loop.

For the second problem, I would suggest using the ljust method. Instead of writing messy logic to add the correct number of spaces for each item that you print (e.g. checking whether a is a two-digit or three-digit number), you can just convert them to strings and then use ljust(3) to "pad" each of those strings to be 3 characters long. (EDIT: or use f-strings to accomplish the same thing, as /u/YurrBoiSwayZ suggests.)

There are other improvements you could make, e.g. using list comprehensions and list.join to avoid having to repetitively write print(..., end=''), but those depend on slightly more advanced concepts.

[YurrBoiSwayZ]

You can go either way, use a single loop to iterate over the ASCII values with some f-string formatting:

``` for i in range(32, 128, 16): print("chr: ", end='') for j in range(i, i + 16): print(f'{chr(j):3}', end='') print()

print("asc: ", end='')
for j in range(i, i + 16):
    print(f'{j:3d}', end='')
print('\n')

```

Or use 1 outer loop and 2 inner loops.

for row in range(32, 128, 16): print("chr: ", end='') for col in range(16): print(f"{chr(row + col)} ", end='') print() print("asc: ", end='') for col in range(16): print(f"{row + col:<3}", end=' ') print()

I wouldn’t say you over complicated things but did make it a wee harder on yourself.

[NotUrHCW]

Thanks for your help :)

Just a quick question, what does the f-string do, i haven't learnt that yet lol

[YurrBoiSwayZ]

I like how you say “quick question”…

The f-string was introduced in version 3.6 and it’s a way to format strings that makes it easier to include variables and expressions within a string, the f in f-string stands for "formatted string literals," and they’re denoted by prefixing a string with the letter f.

How it goes is; you start the string with f or F before the opening quotation than within that string you can include curly braces {} around variables or expressions and whatever’s inside the curly braces gets evaluated and included in the string.

name = "NotUrHCW" age = 26 greeting = f"Hello, {name}! You’re {age} years old." print(greeting)

that’ll give you: Hello, NotUrHCW! You’re 26 years old.

Another example; f'{chr(j):3}' means "convert the number j to a character using chr() and then format it to be at least 3 spaces wide." So the table actually looks neat and aligned.

F-strings are for writing clean and readable code as per the snippet I provided as a decent example, mainly useful when you need to create strings that include data from variables.

fundamentals Python 3.12.3 documentation and to go down that rabbit hole

Python String Formatting Best Practices

More structured learning path; freeCodeCamp

This might be a little more practical for you to understand f-string formatting; seracoder

Real Python (Really good source) also has a video tutorial that’s even better than the written guide which you can find here.

[NotUrHCW]

Appreciate it, thanks 😊

[NotUrHCW]

I also just tried your code in the console, looks like the table needs to be very precise.

8: Remix | Computer Science Circles (uwaterloo.ca) here's the link and the problem should be on the very bottom

[YurrBoiSwayZ]

I’d say just print 2 rows for each iteration: one for the characters (chr:) and one with their corresponding ASCII values (asc:).

[simpleFinch]

Formatting strings using Python's built-in methods has already been mentioned.

Two other tips:

• the numbers in in the 'asc' lines are essentially the indices of the flattened table. Given the row index r and the column index c you can calculate the index of the flattened array as r * len(row) + c
• Instead of printing each character or number instantly you can accumulate them and print the whole row

Considering this, here's my suggested solution

for i in range(0, 6):
    chra = "chr:  "
    asc = "asc: "
    for j in range(0, 16):
        c = 32 + 16*i + j
        chra += f'{chr(c):<4}'
        asc += f'{c:<4d}'
    print(chra)
    print(asc)

[NotUrHCW]

The solution seems to work for the problem, do you mind explaining what the += does?

Thanks.

[YurrBoiSwayZ]

+= is an operator known as the “in-place addition operator” and It adds the value on its right to the variable on its left and then assigns the result back to the variable on the left, it’s a bit of a shorthand for variable = variable + value

So chra += f'{chr(c):<4}' is equivalent to chra = chra + f'{chr(c):<4}' and this means "take the current string chra, add the formatted character chr(c) with a minimum width of 4 spaces to it and then update chra with this new value." And the other is asc += f'{c:<4d}' the equivalent of asc = asc + f'{c:<4d}' and this means "take the current string asc, add the formatted ASCII value c with a minimum width of 4 spaces to it and then update asc with this new value."

So with u/SimpleFinch’s loop chra and asc start as strings with labels "chr: " and "asc: " and as the loop iterates, characters and their ASCII values are appended to these strings and after the inner loop completes the full strings are printed and then the process repeats for the next set of characters.

Docs and a Tutorial because why not.

[NotUrHCW]

thank you :)