April 19, 2019

1. Tuples

• Tuples are defined with (), arrays are defined with [], and once the definition is complete, tuples cannot be modified. Tuples can hold different types of data types / feel a little like structures in C++.
• Define empty tuples

empty_typle = ()

• Tuples/definitions containing only one element need to be comma

empty_typle = (5)    #  It is of type int
empty_typle = (5，)  #  It is a tuple tuple type

• Common operations for tuples

info_tuple = ("zhangsan", "zhangsan", 18, 175)
# 1. Value and Index
print(info_tuple[0])
print(info_tuple.index("zhangsan"))
# 2. Statistical Count
print(info_tuple.count("zhangsan"))
# 3. Number of statistical tuples
print(len(info_tuple))

# 4. Traversal of tuples
info_tuple = ("zhangsan", 18, 1.75)
for my_info in info_tuple:
    print(my_info)

• Scenarios:

(1) Parameters and return values of functions

(2) Format string

infor = ("Xiao Ming", 18, 175)  #This is the tuple
print("%s Age is:%d Height is %.2f" % infor)

(3) Keep the list unmodified to ensure its security

• Conversion of tuples and lists
  list = typle[. . . ]
  tuple = list(. . . )

2. Dictionaries

• The difference between a list and a dictionary is that a list is an ordered data collection and a dictionary is an unordered data collection.(out of order: don't care about the data saved), it feels like a structure.Keys must be unique when using a dictionary
• Definition of dictionary:

# 1. Definition of dictionary variables
xiaoming = {"name": "Xiao Ming",   # Dictionary out of order, not concerned with output order
            "age": 18,
            "genfer": True,
            "height": 1.75,
            "weignt": 75.5}

• Dictionary Operation

# 2. Value
print("The user's name is:%s" % xiaoming["name"])
# 3. Add, delete
xiaoming["school"] = "CUMT"   # k does not add, it modifies if it exists
# 4. Delete
xiaoming.pop("name") # Delete name
# 5. Statistics
print(len(xiaoming))
# 6. Merge Dictionaries
asd = {"add": "papa"}
xiaoming.update(asd)
# 7. Empty Dictionary
xiaoming.clear()

• Traversal of dictionaries

# 8. Loop through the dictionary, and the variable k is the key value each time it gets
for k in xiaoming:
    print("%s -- %s  " % (k, xiaoming[k]))

• Scenario for dictionaries and lists: Use dictionaries to define information about objects, placing individual objects in a list one by one

card_list = [
    {"name": "zhangsan,",
     "qq": "123456,",
     "phone": "18252115105"
     },
    {"name": "lisi",
     "qq": "1666364106",
     "phone": 18795387502}
]
for card_info in card_list:
    print(card_info)

Run Results

E:\pro\05_Advanced Data Type\venv\Scriptspython.exe E:/pro/05_Advanced Data Type/hm_11_List Dictionary Application Scenario.py
{'name': 'zhangsan,', 'qq': '123456,', 'phone': '18252115105'}
{'name': 'lisi', 'qq': '1666364106', 'phone': 18795387502}

3. ==String==

• Define the string, note the use of single and double quotation marks

# 1. Definition of strings
str1 = "heelo python"
str2 = 'My nickname is"Big watermelon"'

• 0. Basic operations for string operations

# 2.len() statistical length
print(len(str1))
# 3. Count occurrences of small strings
print(str1.count("llo"))
# 4. Determine where the substring appears
print(str1.index("llo"))

• 1. Type of judgment for string operations

# 5.isspace() returns TRUE if it determines a blank character, etc. (tabs, whitespace is a blank character)
print(space_str.isspace())
# 6. Determine if the string contains only numbers
print(str1.isdecimal())
print(str1.isdigit())
print(str1.isnumeric())

• 2. Finding and Replacing String Operations

# 7. Find the specified string
print(str1.startswith("hello"))    # Whether to start with the specified string
print(str1.endswith("hello"))      # Whether to end at the specified location
print(str1.find("llo"))            # Note the difference between index and index
# 8. Replace
print(str1.replace("hello", "python"))  # replace forms a new string without changing the original string
print(str1)

• 3. The text of a string operation is against it

# 9. String text vs.
poem = ["Yellow Crane Tower",
        "Wang Huanzhi",
        "Day by Day",
        "Yellow River inflow",
        "in order to see far away",
        "Move Up One Level"]
for poem_str in  poem:
    print("|%s|" % poem_str.center(10, " "))

• 4. String operations to remove white space characters

# 10. Remove whitespace characters
    print(poem_str.strip())

• 5. Split and connect

poem = "Yellow Crane Tower, Wang Huanzhi, Day by Day\t ,Yellow River inflow, in order to see far away\n,Move Up One Level"
print(poem)
# 11. Split String
poem_list = poem.split()
print(poem_list)
print(poem)
# 12. Merge strings use "" as separator
result = " ".join(poem_list)
print(result)

• 6. ==Slice of string==

# 13. String's slice python provides a backward index, followed by -1, the value between the range of the slice index
num = "0123456789"
print(num[2:6])
print(num[2:])
print(num[:6])
print(num[:])
print(num[::2])
print(num[1::2])
print(num[-1])
print(num[2:-1])
print(num[::-1])  # Get Reverse Order
print(num[::-2])

4. Common methods: Common methods for advanced data types