Checkpoint: Python Essentials for Analysts

Five questions on this section. Answer all of them, then see your score and why each answer is right or wrong.

What does this print?

Python

prices = {"Desk Mat XL": 29, "Laptop Stand": 49}
prices["Desk Mat XL"] = prices.get("Desk Mat XL", 0) + 1
print(len(prices), prices["Desk Mat XL"])

2 30
3 30
2 1
A KeyError

A colleague’s function returns 3.3333333333333335 for average([10, 20, 30]) instead of 20.0. What is the bug?

Python

def average(values):
    total = 0
    for v in values:
        total += v
        return total / len(values)

total should start at 1.
len(values) counts characters instead of items.
The return is indented inside the loop, so the function returns after adding the first value.
Python cannot divide integers, so it returns the first value.

Which f-string prints Share: 12.5% when share = 0.125?

f"Share: {share:.1f}%"
f"Share: {share:%}"
f"Share: {share:,.2f}%"
f"Share: {share:.1%}"

A loop over rows stops with TypeError: unsupported operand type(s) for +: 'int' and 'str' on the line total = total + row["quantity"]. What is the most likely fix?

Rename total to something else.
Convert the quantity first: total = total + int(row["quantity"]).
Wrap the line in try / except TypeError and skip the row.
Start total at "" instead of 0.

totals = [65.0, 18.0, 72.0]. What does [t > 50 for t in totals] produce?

[True, False, True]
[65.0, 72.0]
2
A SyntaxError

5 questions unanswered