Python - 列表和任务- 技术经验 -卓越飞翔博客

python - 列表和任务

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

索引

数数

返回str

立即学习“Python免费学习笔记（深入）”；

流行

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

我们必须逐一迭代列表
检查项目是字符串还是其他类型
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't1. 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('t2. 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('t3. updated list by inserting highlighter b/w 2nd &amp;3rd:', delivery_list)

#######################################################################################
# 4. one delivery was canceled. remove “ruler” from the list and print the updated list.
#######################################################################################
delivery_list.remove('ruler')
print('t4. 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('t5. sublist of first three elements using loop:', sublist) 
print('t   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('t6. uppercase list of delivery items:', uppercase_list)

uppercase_list_lc = [item.upper() for item in delivery_list]
print('t6. 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't7. marker is found {is_found} times')
else:
    print(f't7. marker is not found {is_found}')

print(f't8. 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't9. sorted delivery list is {delivery_list}')

delivery_list.reverse()
print(f't10. 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('t11. 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 zip
paired_list=list(zip(delivery_list,delivery_time))
print('tpaired list using zip:', paired_list[0:2])

#combine corresponding item from multiple list using zip and for
item_time_list = [[item,time] for item, time in zip(delivery_list, delivery_time)]
print ('titem_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('t12. the count of ruler in delivery list is:', is_found)

index_pencil = delivery_list.index('pencil')
print(f't13. index of pencil in {delivery_list} is {index_pencil}')

small_list = ['ink','']
delivery_list.extend(small_list)
print('t14. extend list by extend:', delivery_list)

item_time_list.clear()
print('t15. clearing the list using clear():', item_time_list)

notebook_list = ['notebook']*3
print('t16. notebook list is:', notebook_list)

#filter the list with e letter
delivery_list

new_delivery_list = []
for item in delivery_list:
    if 'e' in item:
        new_delivery_list.append(item)

print ('t18. filtered list with items containing e:', new_delivery_list)

new_list_compre = [item for item in delivery_list if 'e' in item]
print ('t18. filtered list by list comprehension:', new_list_compre)

#remove duplicate items
delivery_list.extend(['ink', 'marker'])
print('t   ', delivery_list)

for item in delivery_list:
    if delivery_list.count(item) &gt; 1:
        delivery_list.remove(item)

print('t19. duplicate remove list:',delivery_list)
print('t19. 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 comprehension
nested_list = []
for item in delivery_list:
    nested_list.append([item, len(item)])

print('t17. ', nested_list[-1:-6:-1])

#using list comprehension printing nested list
nested_list = [[item,len(item)] for item in delivery_list]
print('t17. nested list with length:', nested_list[:5])

答案：

PS C:ProjectsPythonSuresh&gt; 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 &amp;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]]

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