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Dictionaries & sets

Key–value maps, uniqueness, counting, grouping, and fast lookups.

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Dictionaries & sets easy

How to Count Elements and Find Duplicates in a Python List

Count occurrences of each element in a list, extract unique values, and identify duplicates using Python dictionaries and sets.

dictionary set counting
Python
def analyze_counts(data):
    """Count elements, return unique values, and find duplicates."""
    
    # Count occurrences using a dictionary
    counts = {}
    for item in data:
        counts[item] = counts.get(item, 0) + 1
    
    # Alternative compact approach with set
    unique_items = set(data)
    
    # Fi…
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