python实现list元素按关键字相加减的方法示例

# coding=utf-8# 两个list按关键字相加或相减def ListAdd(list1, list2, bAdd = True):  if bAdd == False:    list2 = [(k, -v) for (k, v) in list2]  d = {}  list0 = list1 + list2  for (k, v) in list0:    d.setdefault(k, 0)   # 设置字典元素初始值    d[k] += v        # 对字典中的元素按关键字相加  ret = list(d.items())    # 字典转换成list  ret = sorted(ret)      # 对list排序  return retif __name__ == '__main__':  a = [("s1", 10), ("s2", 13), ("s3", 25), ("s7", 30)]  b = [("s1", 22), ("s3", 16), ("s10", 8)]  print("a=", a)  print("b=", b)  ret1 = ListAdd(a, b)    # ret1 = a + b  print("ret1=", ret1)  ret2 = ListAdd(a, b, False) # ret2 = a - b  print("ret2=", ret2)

E:/Program/Python>del.pya= [('s1', 10), ('s2', 13), ('s3', 25), ('s7', 30)]b= [('s1', 22), ('s3', 16), ('s10', 8)]ret1= [('s1', 32), ('s10', 8), ('s2', 13), ('s3', 41), ('s7', 30)]ret2= [('s1', -12), ('s10', -8), ('s2', 13), ('s3', 9), ('s7', 30)]