Question

In: Computer Science

r = range(10, 40, 3) def print_lv(strings): strings = strings if isinstance(strings, list) else [strings] for...

r = range(10, 40, 3)

def print_lv(strings):

strings = strings if isinstance(strings, list) else [strings]

for string in strings:

st = "f'" + string + ": {" + string + "}'"

print_stmt = 'print(' + st + ', end="; ")'

# Uncomment the following print statement to see the statement to be executed.

# Each will appear on a separate line.

# print(f'\n{print_stmt}')

exec(print_stmt)

print()

print_lv(['list(r)', 'r[-2:3:-1]', 'list(r[-2:3:-1])'])

OUTPUT:

list(r): [10, 13, 16, 19, 22, 25, 28, 31, 34, 37]; r[-2:3:-1]: range(34, 19, -3); list(r[-2:3:-1]): [34, 31, 28, 25, 22];

I need help explaining this bit of code. Particularly why r[-2:3:-1] is range(34, 19, -3).

The slice starts at position -2 and stops at position 3 in increments of step -1.

YET the range that results from taking that slice starts at value 34 and stops at value 19 in increments of step -3

Expert Solution

If you need more help, please ask in comments

venereology answered 2 years ago

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