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Python - 列表和任务

百变鹏仔 3天前 #Python
文章标签 列表

学习索引和切片之后,我们开始更多地了解列表和内置方法。方法有

不返回

追加插入删除排序反转清晰

返回整数

返回str

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对于交付列表的较小更改,内置功能本身就足够了。但是当我们想要对列表进行更多操作时,就需要for循环、if循环。

例如,有一个列表 ['pencil', 'notebook', 'marker', 'highlighter', 'glue stick', 'eraser', 'laptop', 3],其中只有字符串需要转换为大写。这里我们不能直接使用列表或字符串方法。理想的逻辑是

  1. 我们必须逐一迭代列表
  2. 检查项目是字符串还是其他类型
  3. 相应地使用字符串方法 upper() 和append()

所以这里for循环,需要if,else条件

delivery_list= ['pencil', 'notebook', 'marker', 'highlighter', 'glue stick', 'eraser', 'laptop', 3]upper_list = []for item in delivery_list:    if type(item) == str:        upper_list.append(item.upper())    else:        upper_list.append(item)print('upper case list is:', upper_list)output:upper case list is: ['pencil', 'notebook', 'marker', 'highlighter', 'glue stick', 'eraser', 'laptop', 3]

给出的任务是更多地练习这些方法和逻辑。找到可用的逻辑或方法很有趣。
解决的细节是

tasks_list.py########################################################################################1. create a list of five delivery items and print the third item in the list. #eg: [“notebook”, “pencil”, “eraser”, “ruler”, “marker”]#######################################################################################delivery_list = ['notebook', 'pencil', 'eraser', 'ruler', 'marker']print (f'	1. third item in the list{delivery_list} is: {delivery_list[2]}')######################################################################################## 2.a new delivery item “glue stick” needs to be added to the list. # add it to the end of the list and print the updated list.#######################################################################################delivery_list.append('glue stick')print('	2. updated delivery list is:', delivery_list)######################################################################################## 3. insert “highlighter” between the second and third items and print the updated list.#######################################################################################delivery_list.insert(2, 'highlighter')print('	3. updated list by inserting highlighter b/w 2nd &3rd:', delivery_list)######################################################################################## 4. one delivery was canceled. remove “ruler” from the list and print the updated list.#######################################################################################delivery_list.remove('ruler')print('	4. updated list after removing ruler is:', delivery_list)######################################################################################## 5. the delivery man needs to deliver only the first three items. # print a sublist containing only these items.#######################################################################################sublist =[]for item in delivery_list[:3]:    #sublist =sublist.append(item)      #this is incorrect as sublist.append() returns none.    sublist.append(item)print('	5. sublist of first three elements using loop:', sublist) print('	   sublist of first three elements using slicing:', delivery_list[:3]) ######################################################################################## 6.the delivery man has finished his deliveries. # convert all item names to uppercase using a list comprehension and print the new list.#######################################################################################uppercase_list=[]for item in delivery_list:    uppercase_list.append(item.upper())print('	6. uppercase list of delivery items:', uppercase_list)uppercase_list_lc = [item.upper() for item in delivery_list]print('	6. uppercase list using list compre:', uppercase_list_lc)######################################################################################## 7. check if “marker” is still in the list and print a message indicating whether it is found.# 8. print the number of delivery items in the list.#######################################################################################is_found= delivery_list.count('marker')if 'marker' in delivery_list:    print(f'	7. marker is found {is_found} times')else:    print(f'	7. marker is not found {is_found}')print(f'	8. number of delivery item from {delivery_list} is: ', len(delivery_list))######################################################################################## 9. sort the list of items in alphabetical order and print the sorted list# 10. the delivery man decides to reverse the order of his deliveries. # reverse the list and print it#######################################################################################delivery_list.sort()print(f'	9. sorted delivery list is {delivery_list}')delivery_list.reverse()print(f'	10. reverse list of delivery list is {delivery_list}')######################################################################################## 11. create a list where each item is a list containing a delivery item and its delivery time. # print the first item and its time.#######################################################################################delivery_list_time = [['letter', '10:00'], ['parcel', '10:15'], ['magazine', '10:45'], ['newspaper', '11:00']]print('	11. first delivery item and time', delivery_list_time[0])delivery_list = ['pencil', 'notebook', 'marker', 'highlighter', 'glue stick', 'eraser', 'laptop']delivery_time = ['11:00','11:20','11:40','12:00','12:30','13:00', '13:30']#paring of two list using zippaired_list=list(zip(delivery_list,delivery_time))print('	paired list using zip:', paired_list[0:2])#combine corresponding item from multiple list using zip and foritem_time_list = [[item,time] for item, time in zip(delivery_list, delivery_time)]print ('	item_time_list using list comprehension: ', item_time_list[0:1])######################################################################################## 12. count how many times “ruler” appears in the list and print the count.# 13. find the index of “pencil” in the list and print it.# 14. extend the list items with another list of new delivery items and print the updated list.# 15. clear the list of all delivery items and print the list.# 16. create a list with the item “notebook” repeated three times and print the list.# 17. using a nested list comprehension, create a list of lists where each sublist contains an item # and its length, then print the new list.# 18. filter the list to include only items that contain the letter “e” and print the filtered list.# 19. remove duplicate items from the list and print the list of unique items.#######################################################################################is_found= delivery_list.count('ruler')print('	12. the count of ruler in delivery list is:', is_found)index_pencil = delivery_list.index('pencil')print(f'	13. index of pencil in {delivery_list} is {index_pencil}')small_list = ['ink','']delivery_list.extend(small_list)print('	14. extend list by extend:', delivery_list)item_time_list.clear()print('	15. clearing the list using clear():', item_time_list)notebook_list = ['notebook']*3print('	16. notebook list is:', notebook_list)#filter the list with e letterdelivery_listnew_delivery_list = []for item in delivery_list:    if 'e' in item:        new_delivery_list.append(item)print ('	18. filtered list with items containing e:', new_delivery_list)new_list_compre = [item for item in delivery_list if 'e' in item]print ('	18. filtered list by list comprehension:', new_list_compre)#remove duplicate itemsdelivery_list.extend(['ink', 'marker'])print('	   ', delivery_list)for item in delivery_list:    if delivery_list.count(item) > 1:        delivery_list.remove(item)print('	19. duplicate remove list:',delivery_list)print('	19. duplicate remove list:',list(set(delivery_list)))######################################################################################## 17. using a nested list comprehension, create a list of lists where each sublist contains an item # and its length, then print the new list.########################################################################################without list comprehensionnested_list = []for item in delivery_list:    nested_list.append([item, len(item)])print('	17. ', nested_list[-1:-6:-1])#using list comprehension printing nested listnested_list = [[item,len(item)] for item in delivery_list]print('	17. nested list with length:', nested_list[:5])

答案:

PS C:ProjectsPythonSuresh> python Tasks_list.py        1. Third item in the list['Notebook', 'Pencil', 'Eraser', 'Ruler', 'Marker'] is: Eraser        2. Updated delivery list is: ['Notebook', 'Pencil', 'Eraser', 'Ruler', 'Marker', 'Glue Stick']        3. Updated list by inserting Highlighter b/w 2nd &3rd: ['Notebook', 'Pencil', 'Highlighter', 'Eraser', 'Ruler', 'Marker', 'Glue Stick']        4. Updated list after removing Ruler is: ['Notebook', 'Pencil', 'Highlighter', 'Eraser', 'Marker', 'Glue Stick']        5. Sublist of first three elements using loop: ['Notebook', 'Pencil', 'Highlighter']           Sublist of first three elements using slicing: ['Notebook', 'Pencil', 'Highlighter']        6. Uppercase list of delivery items: ['NOTEBOOK', 'PENCIL', 'HIGHLIGHTER', 'ERASER', 'MARKER', 'GLUE STICK']        6. Uppercase list using list compre: ['NOTEBOOK', 'PENCIL', 'HIGHLIGHTER', 'ERASER', 'MARKER', 'GLUE STICK']        7. Marker is found 1 times        8. Number of delivery item from ['Notebook', 'Pencil', 'Highlighter', 'Eraser', 'Marker', 'Glue Stick'] is:  6        9. Sorted delivery list is ['Eraser', 'Glue Stick', 'Highlighter', 'Marker', 'Notebook', 'Pencil']        10. Reverse list of delivery list is ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser']        11. First delivery item and time ['Letter', '10:00']        Paired list using zip: [('Pencil', '11:00'), ('Notebook', '11:20')]        Item_time_list using list comprehension:  [['Pencil', '11:00']]        12. The count of Ruler in delivery list is: 0        13. Index of Pencil in ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser', 'Laptop'] is 0        14. Extend list by extend: ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser', 'Laptop', 'Ink', '']        15. Clearing the list using clear(): []        16. Notebook list is: ['Notebook', 'Notebook', 'Notebook']        18. Filtered list with items containing e: ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser']        18. Filtered list by list comprehension: ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser']            ['Pencil', 'Notebook', 'Marker', 'Highlighter', 'Glue Stick', 'Eraser', 'Laptop', 'Ink', '', 'Ink', 'Marker']        19. Duplicate remove list: ['Pencil', 'Notebook', 'Highlighter', 'Glue Stick', 'Eraser', 'Laptop', '', 'Ink', 'Marker']        19. Duplicate remove list: ['', 'Ink', 'Pencil', 'Notebook', 'Marker', 'Eraser', 'Laptop', 'Highlighter', 'Glue Stick']        17.  [['Marker', 6], ['Ink', 3], ['', 0], ['Laptop', 6], ['Eraser', 6]]        17. Nested list with length: [['Pencil', 6], ['Notebook', 8], ['Highlighter', 11], ['Glue Stick', 10], ['Eraser', 6]]