通过第一列的元素合并矩阵的Python程序

给定一个矩阵，根据第一列中的元素进行合并。

Input : test_list = [[4, “geeks”], [3, “Gfg”], [4, “CS”], [4, “cs”], [3, “best”]] 
Output : [[4, ‘geeks’, ‘CS’, ‘cs’], [3, ‘Gfg’, ‘best’]] 
Explanation : 4 is paired with geeks, CS and cs hence are merged into 1 row.

Input : test_list = [[4, “geeks”], [3, “Gfg”], [4, “CS”], [5, “cs”], [3, “best”]] 
Output : [[4, ‘geeks’, ‘CS’, ‘cs’], [3, ‘Gfg’, ‘best’], [5, ‘cs’]] 
Explanation : 4 is paired with geeks and CS hence are merged into 1 row. 
 

方法 1：使用 setdefault() 和列表推导

在这种情况下，分组任务是使用 setdefault() 完成的，它将键分配为第一列元素，其余元素作为列表的值。列表理解用于从构造的字典中获取所有值。

Python3

# initializing list
test_list = [[4, "geeks"], [3, "Gfg"], [4, "CS"], 
             [4, "cs"], [3, "best"]]
  
# printing original list
print("The original list is : " + str(test_list))
  
res = {}
for key, val in test_list:
  
    # setdefault used to merge similar values
    res.setdefault(key, []).append(val)
  
# getting all values
res = [[key] + val for key, val in res.items()]
  
# printing result
print("Merged Matrix : " + str(res))

输出：

The original list is : [[4, ‘geeks’], [3, ‘Gfg’], [4, ‘CS’], [4, ‘cs’], [3, ‘best’]]
Merged Matrix : [[4, ‘geeks’, ‘CS’, ‘cs’], [3, ‘Gfg’, ‘best’]]

方法 2：使用 values() 和 setdefault()

在这里，我们使用 values() 提取值，其余所有操作都以与上述类似的方式执行。该程序根据执行的分组从列表中省略了第一列元素。

蟒蛇3

# initializing list
test_list = [[4, "geeks"], [3, "Gfg"], [4, "CS"],
             [4, "cs"], [3, "best"]]
  
# printing original list
print("The original list is : " + str(test_list))
  
res = {}
for key, val in test_list:
  
    # setdefault used to merge similar values
    res.setdefault(key, []).append(val)
  
# fetch values using value()
res = list(res.values())
  
# printing result
print("Merged Matrix : " + str(res))

输出：

The original list is : [[4, ‘geeks’], [3, ‘Gfg’], [4, ‘CS’], [4, ‘cs’], [3, ‘best’]]
Merged Matrix : [[‘geeks’, ‘CS’, ‘cs’], [‘Gfg’, ‘best’]]