Dictionaries – Iteration
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. for key in d: what does key get?
2. How do you loop through values?
3. How do you loop through keys AND values?
4. d = {'a':1, 'b':2}\nfor k in d:\n print(k)\nWhat prints?
5. d = {'x':10}\nfor k, v in d.items():\n print(k, v)\nWhat prints?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1d = {'a':1} for k, v in d: print(k, v) | AOutput: a b | |
| 2d = {'x':1} d['x'] += 1 del d['x'] print(d['x']) | BError: Key deleted, KeyError | |
| 3for k, v in d.items(): print(k, v) | COutput: x 10 | |
| 4if 'name' in d: print(d['name']) | DValid: Unpack key and value | |
| 5d = {'a':1,'b':2} for k in d: print(k) | EOk: Check key before accessing | |
| 6d = {'x':10} for k,v in d.items(): print(k,v) | FError: Must use d.items() |
C
Definitions
for key in d:
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
for key __ d:
print(key)
2.
for val in d.______():
print(val)
3.
for k, v in d._____():
print(k, v)
4.
if 'name' __ d:
print('Found')
5.
for key in d:
print(d[___])
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
d = {'a': 1, 'b': 2}
B
for k, v in d:
C
print(k, v)
D
print('Done')
Question 2
A
d = {'a': 1, 'b': 2}
B
for val in d:
C
print(val)
D
# expects values
Question 3
A
d = {'a': 1, 'b': 2}
B
for k, v in d.keys():
C
print(k, v)
D
print('Done')
Question 4
A
d = {'a': 1, 'b': 2}
B
for k in d.items():
C
print(k)
D
print('Done')
Question 5
A
found = 'Alice' in {'name': 'Alice', 'age': 12}
B
d = {'name': 'Alice', 'age': 12}
C
print('Found:', found)
D
# expects True
Answer Key
Dictionaries – Iteration
Section A: Quick Questions
Q1
A — Each key, one at a time
Q2
A — for v in d.values():
Q3
A — for k, v in d.items():
Q4
B — a then b
Q5
B — x 10
Section B: Match the Pairs
Q1
d = {'a':1}
for k, v in d:
print(k, v) → Error: Must use d.items()
Q2
d = {'x':1}
d['x'] += 1
del d['x']
print(d['x']) → Error: Key deleted, KeyError
Q3
for k, v in d.items():
print(k, v) → Valid: Unpack key and value
Q4
if 'name' in d:
print(d['name']) → Ok: Check key before accessing
Q5
d = {'a':1,'b':2}
for k in d:
print(k) → Output: a
b
Q6
d = {'x':10}
for k,v in d.items():
print(k,v) → Output: x 10
Section C: Definitions
Q1
for key in d: — Iterate through all keys in the dictionary.~~for v in d.values():Section D: Fill in the Blanks
Q1
for key in d:
print(key)Q2
for val in d.values():
print(val)Q3
for k, v in d.items():
print(k, v)Q4
if 'name' in d:
print('Found')Q5
for key in d:
print(d[key])Section E: Spot the Error
Q1
B — Looping over d directly gives only keys. Use .items() for key-value pairs.
Q2
B — for val in d: gives KEYS, not values. Use .values() for values.
Q3
B — .keys() only gives keys. Use .items() to get both key and value.
Q4
B — Without unpacking, k is a tuple like ('a', 1). Use k, v to unpack.
Q5
A — 'in' checks KEYS by default. To check values, use d.values().