通常,我们需要找到特定值所在的索引。有很多方法可以使用index()等来实现。但是,有时需要查找特定值的所有索引,以防它在列表中多次出现。
# using filter()# initializing list test_list = [1, 3, 4, 3, 6, 7] # printing initial list print ("Original list : " + str(test_list)) # using filter()# to find indices for 3 res_list = list(filter(lambda x: test_list[x] == 3, range(len(test_list)))) # printing resultant list print ("New indices list : " + str(res_list)) # using enumerate()# initializing list test_list = [1, 3, 4, 3, 6, 7] # printing initial list print ("Original list : " + str(test_list)) # using enumerate()# to find indices for 3 res_list = [i for i, value in enumerate(test_list) if value == 3] # printing resultant list print ("New indices list : " + str(res_list)) # using list comprehension # initializing list test_list = [1, 3, 4, 3, 6, 7] # printing initial list print ("Original list : " + str(test_list)) # using list comprehension # to find indices for 3 res_list = [i for i in range(len(test_list)) if test_list[i] == 3] # printing resultant list print ("New indices list : " + str(res_list)) # using naive method # initializing list test_list = [1, 3, 4, 3, 6, 7] # printing initial list print ("Original list : " + str(test_list)) # using naive method # to find indices for 3 res_list = [] for i in range(0, len(test_list)) : if test_list[i] == 3 : res_list.append(i) # printing resultant list print ("New indices list : " + str(res_list))
输出结果
Original list : [1, 3, 4, 3, 6, 7] New indices list : [1, 3] Original list : [1, 3, 4, 3, 6, 7] New indices list : [1, 3] Original list : [1, 3, 4, 3, 6, 7] New indices list : [1, 3] Original list : [1, 3, 4, 3, 6, 7] New indices list : [1, 3]