Front
Variables: letters, numbers, underscores, etc., do not use keywords
python is case sensitive
Comments are handled with #
list
You can use positive and negative indexes to access elements in the list (the absolute value of the difference between the positive and negative indexes is the list size)
slice access
list[start:end]: Returns a list of left-closed and right-open intervals from index start to index end [start, end)
list[start:end:step]: Returns a list of left-open and right-closed intervals from index start to index end with a step size of step
- start can be omitted if the slice starts at 0
- If the slice ends at the last element, end can be omitted
- If the slice step is 1, you can omit: step
list add list.append(XXX)
list delete del list[index]
Supports the addition of multiple lists to generate a new large list, similar to list accumulation
Support list multiplication by integer to form a new list (multiplier<1, return an empty list, multiplier==1, return a new list with the same elements of the original list, multiplier greater than 1, it is analogous to the accumulation of multiple lists)
len(list): returns the number of elements in the list
Tuple
It is similar to a list in use, enclosed in parentheses, the biggest difference is that the ancestor element cannot be modified
Yuanzu uses [] instead of () when taking values and slicing functions
Dictionary (Dict)
kv storage method, {aa:AA,bb:BB}, the value is obtained through the key key, and the method of obtaining the value dir[key], yes, also through [], returns the value if it exists, and returns None if it does not exist
Addition and modification: dir[key]=new_value If there is one, change it and if not, add it
Delete: del dir[key]
Traverse keys: dirc.keys()
Traversing values: dirc.values()
Circumstances kv: for k,v in dirc.items()
other
range(): range, which returns a collection
range(5)==range(0,5) left closed right open interval
range(1,10,2) within the range of [1,10) with a step size of 2 for the range of values
Python commonly used standard modules
random: Randomly selected function
os: interaction with the operating system
sys: system-related operations
time: interaction with time
math: Interaction with mathematics
re: tools that provide regular expressions for advanced string processing