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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsTo loop over a dictionary’s existing keys and values, use my_dict.items(). To create a dictionary from separate, positionally aligned keys and values, use dict(zip(keys, values)). Passing dictionaries directly to zip() pairs their keys, because iterating over a dictionary produces its keys.
Loop through a dictionary’s key/value pairs
If the keys and values are already in one dictionary, iterate over its .items() view. It yields each key together with its value, so there is no need to call zip().
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my_dict = {"name": "Lancelot", "quest": "the Holy Grail"}
for key, value in my_dict.items():
print(key, value)This is the direct pattern shown in the Python 3.13.15 data structures tutorial.
Build a dictionary from separate keys and values
When two iterables hold corresponding keys and values in the same order, zip() pairs elements at matching positions. Passing those pairs to dict() creates the mapping.
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keys = ["name", "quest", "favorite color"]
values = ["Lancelot", "the Holy Grail", "blue"]
answers = dict(zip(keys, values))
print(answers)
# {'name': 'Lancelot', 'quest': 'the Holy Grail', 'favorite color': 'blue'}zip() pairs by position; it does not determine a relationship from the elements’ labels or contents. The two iterables must already be aligned as intended.
Choose what should happen if lengths differ
By default, zip() stops as soon as its shortest input runs out. In a dictionary-building expression, any remaining elements in a longer input are left unused. If unequal lengths indicate invalid data, use strict=True:
result = dict(zip(keys, values, strict=True))With strict=True, Python raises ValueError if the iterables have different lengths. This option requires Python 3.10 or newer. If stopping at the shorter input is intentional, ordinary zip() is suitable. If you need to pad the shorter input instead, use itertools.zip_longest(). These behaviors are documented in the Python built-in functions reference.
Pair entries from two dictionaries
Use zip() on both dictionaries’ .items() views to pair their entries by iteration position:
dict1 = {"a": 1, "b": 2}
dict2 = {"x": 10, "y": 20}
for (key1, value1), (key2, value2) in zip(dict1.items(), dict2.items()):
print(key1, value1, key2, value2)This matches the first entry from one dictionary with the first entry from the other, the second with the second, and so on. It does not find entries with equal keys or infer a shared record identity. If the goal is to compare values by key, express that key-based relationship explicitly instead of relying on position.
If you write zip(dict1, dict2) without .items(), the resulting pairs are keys, not key/value pairs. The Python built-in types reference describes dictionaries as iterating over their keys.
Reverse a dictionary when its values are unique
To swap keys and values, zip the value and key views in the same dictionary iteration order, then build a new dictionary:
original = {"name": "Lancelot", "quest": "the Holy Grail"}
reversed_dict = dict(zip(original.values(), original.keys()))Dictionary key and value views iterate in insertion order, which keeps each value paired with its original key. The result works as a complete reversal only if the original values are unique and hashable, so they can be dictionary keys.
If two original keys share a value, the reversed dictionary cannot retain both associations under that one key: dictionary keys are unique, and a later pair overwrites an earlier value. When values repeat, group the original keys into lists under each value instead of trying to make a one-to-one reversal.
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