FAQ: Loops - While Loops: Lists

Frequently Asked Questions Uncategorized
25

I don’t know if you are looking for an explanation, but in case someone bumps into this and wants one, here it it:

I understand you have the folowing code:

python_topics = [“variables”, “control flow”, “loops”, “modules”, “classes”]
#Your code below:
length = len(python_topics)
index = 0
while length < index:
print("I am learning about " + python_topics[index])
index += 1

Syntactically it is correct, but the best practice is to select the condition as the variable that will update within the loop.

I understand this is the reason from CodeAcademy they preferred to not accept this option.

26

Hi,

what purpose does [index] serve in the print statement?

print('I am learning about ’ + python_topics[index])

image

28

can this implementation of python do arithmetic on hexadecimal integers?

29
30

how do you make it print to the… terminal? in hex?
also, if it’s possible to print a list of items without the on one line, how?

31 
>>> print (hex(65535))
0xffff
>>> print (f"{str(hex(65535))[:2]}{str(hex(65535))[2:].upper()}")
0xFFFF
>>>

To print a list with the commas,

>>> print (f"{str(list('abcdefgh'))[1:-1]}")
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'
>>>

Down the rabbit hole…

>>> from functools import reduce
>>> print (reduce(lambda a, b: a + f", {b}", 'abcdefgh'))
a, b, c, d, e, f, g, h
>>>
32

rabbit hole indeed.
print a list on one line/print statement without any symbols(the brackets and commas)

1 Like
33

I have the exact same question but I don’t see a response! Anyone??? Please?

34

Python lists are zero-indexed i.e. the first element is at index 0, the second element is at index 1 and so on. To access a specific element of a list, we can do so by writing the list’s name followed by square brackets with the index of the element we want to access.

myList = ["a", "b", "c", "d", "e"]

# Printing second element of list
print(myList[1])
# "b"

# Printing fourth element of list
print(myList[3])
# "d"

In the exercise, python_topics is a list whose elements are strings.

python_topics = ["variables", "control flow", "loops", "modules", "classes"]

A while loop is being used in the exercise to iterate over the index i.e. in the first iteration, index will be 0, in the second iteration, index will be 1 and so on.
But we don’t want to print the index. Instead we want to print the element at that particular index.
python_topics[index] will allow us to access the string element at that particular index.

print('I am learning about ' + python_topics[index])

In each iteration of the while loop, the + operator will concatenate/join the string 'I am learning about ' with one of the string elements so that we get outputs such as:

"I am learning about variables"
"I am learning about control flow"
...