Python 3字典合并及列表元素添加、多地点员工工时合并需求

Alright, let's walk through these two Python 3 tasks step by step—both are common data wrangling scenarios, so I'll share practical, easy-to-follow code for each.

Task 1: Merge Dictionaries & Combine List Values for Shared Keys #

Suppose you have two dictionaries where some keys map to lists, and you want to merge them: for keys that exist in both, you'll append the list elements together; for unique keys, you just keep their original values. Here's a straightforward approach:

Example Code #

dict_a = {"fruits": ["apple", "banana"], "vegetables": ["carrot"]}
dict_b = {"fruits": ["orange"], "grains": ["rice", "wheat"]}

# Initialize our merged dictionary
merged_dict = {}

# Grab all unique keys from both dictionaries
all_keys = set(dict_a.keys()).union(set(dict_b.keys()))

for key in all_keys:
    # Collect values from both dicts (if they exist)
    combined_values = []
    if key in dict_a:
        combined_values.extend(dict_a[key])
    if key in dict_b:
        combined_values.extend(dict_b[key])
    merged_dict[key] = combined_values

print(merged_dict)
# Output: {'fruits': ['apple', 'banana', 'orange'], 'vegetables': ['carrot'], 'grains': ['rice', 'wheat']}

If you prefer a more concise method using collections.defaultdict, this works too:

from collections import defaultdict

merged_dict = defaultdict(list)
for d in [dict_a, dict_b]:
    for key, val_list in d.items():
        merged_dict[key].extend(val_list)

# Convert back to a regular dictionary if needed
merged_dict = dict(merged_dict)

Task 2: Merge Cross-Location Employee Hours Data #

For this task, we need to combine time entries for employees who appear in multiple locations, summing their daily hours (I'll also include tracking all locations they worked at, since that's useful context). Let's start with sample data, then build the solution.

Sample Input Data #

employee_times = [
    {"LOCATION": "NYC", "NAME": "name_1", "MON": 8, "TUES": 7, "WED": 8, "THURS": 8, "FRI": 7},
    {"LOCATION": "LA", "NAME": "name_1", "MON": 6, "TUES": 8, "WED": 7, "THURS": 8, "FRI": 8},
    {"LOCATION": "CHI", "NAME": "name_2", "MON": 8, "TUES": 8, "WED": 8, "THURS": 8, "FRI": 8}
]

Solution Code #

merged_employees = {}

for entry in employee_times:
    name = entry["NAME"]
    # If the employee isn't in our merged dict yet, add them with initial data
    if name not in merged_employees:
        merged_entry = entry.copy()
        # Store locations as a list to track all work sites
        merged_entry["LOCATION"] = [entry["LOCATION"]]
        merged_employees[name] = merged_entry
    else:
        # Sum up daily hours for the existing employee entry
        merged_entry = merged_employees[name]
        merged_entry["MON"] += entry["MON"]
        merged_entry["TUES"] += entry["TUES"]
        merged_entry["WED"] += entry["WED"]
        merged_entry["THURS"] += entry["THURS"]
        merged_entry["FRI"] += entry["FRI"]
        # Add the new location to their list
        merged_entry["LOCATION"].append(entry["LOCATION"])

# Convert the dictionary values to a list if you want a clean output format
result_list = list(merged_employees.values())

# Print the final merged data
for emp in result_list:
    print(emp)

Output #

{'LOCATION': ['NYC', 'LA'], 'NAME': 'name_1', 'MON': 14, 'TUES': 15, 'WED': 15, 'THURS': 16, 'FRI': 15}
{'LOCATION': ['CHI'], 'NAME': 'name_2', 'MON': 8, 'TUES': 8, 'WED': 8, 'THURS': 8, 'FRI': 8}

If you don't need to track all locations, just remove the parts that handle the LOCATION list—focus solely on summing the daily hours.

内容的提问来源于stack exchange，提问作者Cesar Rodriguez