Python built-in functions Daquan (category)

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python built-in functions

Recently, I've been looking at Python's document, and I'm going to focus on the basics. Python's keyword, build-in Function, build-in Constants, build-in Types, build-in Exception these four aspects, in fact, when looking at the whole "the Python Standard Library" chapter is very good, which describes a lot of good topics. First of all, build-in function list, beginner's understanding, classification may be inaccurate, communicate together.

first, the mathematical operation class
ABS (x) Seek absolute value
1, the parameters can be integral type, can also be plural
2, if the parameter is a complex number, then return the modulus of the complex
Complex ([real[, Imag]]) Create a complex number
Divmod (A, B) Separate fetch and remainder
Note: integral, floating-point types can be
float ([x]) Converts a string or number to a float. If no parameter is returned 0.0
int ([x[, Base]]) Converts a character to an int type, and base represents the binary
Long ([x[, Base]]) Converts a character to a long type
Pow (x, y[, z]) Returns the Y power of X
Range ([start], stop[, step]) Produces a sequence that starts with 0 by default
Round (x[, N]) Rounded
Sum (iterable[, start]) Sum the Set
Oct (x) Convert a number to 8 binary
Hex (x) Converts an integer x to a 16-binary string
Chr (i) Returns the ASCII character corresponding to the integer i
Bin (x) Converts an integer x to a binary string
BOOL ([x]) Convert X to Boolean type

second, the collection class operation
Basestring () Super class for STR and Unicode
cannot be called directly and can be used as isinstance judgment
Format (value [, Format_spec]) Formatting the output string
Formatted parameter order starting from 0, such as "I am {0},i like {1}"
UNICHR (i) Returns the Unicode of the given int type
Enumerate (sequence [, start = 0]) Returns an enumerable object that returns a tuple for the next () method of the object.
ITER (o[, Sentinel]) Generates an iterator for an object, and the second parameter represents a delimiter
Max (iterable[, args ...] [Key]) Returns the maximum value in the collection
Min (iterable[, args ...] [Key]) Returns the minimum value in the collection
Dict ([ARG]) Create a data dictionary
List ([iterable]) To convert a collection class to another collection class
Set () Set Object instantiation
Frozenset ([iterable]) Produces an immutable set
STR ([object]) Convert to String type
Sorted (iterable[, cmp[, key[, reverse]]) Team Collection Sort
Tuple ([iterable]) Generate a tuple type
Xrange ([start], stop[, step]) The xrange () function is similar to range (), but xrnage () does not create a list, but instead returns a Xrange object that behaves like a list, but calculates the list value only when it is needed, which saves us memory when the list is large.

third, logical judgment
All (iterable) 1, the elements in the collection are true when they are true
2, special, if the empty string returned to True
Any (iterable) 1, the elements in the collection have a true time for the true
2, special, if the empty string returned to False
CMP (x, y) If x < Y, returns a negative number; x = = y, returns 0;x > y, returns a positive number

Iv. Reflection
Callable (object) Checks whether object objects can be called
1, the class is can be called
2. Instances cannot be invoked unless the __call__ method is declared in the class
Classmethod () 1, annotations, to illustrate this way is a class method
2. Class methods can be called by the class or by instance
3. The class method is similar to the static method in Java
4. The self parameter is not required in a class method

compile (source, filename,

mode[, flags[, Dont_inherit])

compile source as code or AST object. The code object can be evaluated by EXEC statement execution or eval ().
2, parameter filename: code file name, and pass some recognizable values if the code is not read from the file.
3, parameter model: Specifies the kind of compiled code. can be specified as ' exec ', ' eval ', ' single '.
Dir ([Object]) 1, without parameters, returns the list of variables, methods, and definitions in the current scope;
2, with parameters, returns the properties of the parameter, the method list.
3. If the parameter contains method __dir__ (), the method will be called. When the argument is an instance.
4. If the parameter does not contain __dir__ (), the method will collect the parameter information to the maximum
Delattr (object, name) Delete an object named Name property
eval (expression [, globals [, locals]]) Evaluates the value of an expression
ExecFile (filename [, globals [, locals]]) The usage is similar to exec (), the difference is that the execfile parameter filename is the file name, and the exec parameter is a string.
Filter (function, iterable) Constructs a sequence that is equivalent to [item for item ' in Iterable if function (item)]
1, Parameter function: Return a value of TRUE or false functions, can be none
2. Parameter iterable: A sequence or an iterative object
GetAttr (object, name [, Defalut]) Gets the properties of a class
Globals () Returns a dictionary that describes the current global symbol table
Hasattr (object, name) Determines whether the object contains an attribute named name
Hash (object) Returns the hash value of object if object is a hash table type
ID (object) Returns the unique identity of an object
Isinstance (object, ClassInfo) Determine if object is an instance of class
Issubclass (class, ClassInfo) Determine if it is a subclass
Len (s) Return collection length
Locals () Returns the current list of variables
Map (function, iterable, ...) Iterate through each element to perform a function operation
Memoryview (obj) Returns an object of a memory image type
Next (iterator[, default]) Similar to ()
Object () Base class
Property ([Fget[, fset[, fdel[, Doc]]) The wrapper class for property access, which can be set to access the setter and getter via C.x=value, etc.
Reduce (function, iterable[, initializer]) The merge operation, which starts with the first two parameters, and then the first two results are processed with the third merge, and so on
Reload (module) Reload Module
SetAttr (object, name, value) Setting property values
Repr (object) Changing an object to a printable format
Slice ()  
Staticmethod Declares a static method, which is an annotation
Super (type[, Object-or-type]) Referencing a parent class
Type (object) Returns the type of the object
VARs ([object]) Returns the variable of the object, if no argument is similar to the Dict () method
ByteArray ([Source [, encoding [, errors]]) Returns a byte array
1, if source is an integer, returns an initialized array of length source;
2. If source is a string, the string is converted to a sequence of bytes according to the specified encoding;
3. If source is an iterative type, the element must be an integer in [0, 255];
4. If source is an object that is consistent with the buffer interface, this object can also be used to initialize the ByteArray.
Zip ([iterable, ...]) is not understand, just see the matrix of the changing aspects

v. IO operation
File (filename [, mode [, BufSize]]) A constructor for the file type that opens a file that is created if the file does not exist and mode is write or append. Adding ' B ' to the mode parameter will manipulate the file in binary form. Adding ' + ' to the mode parameter will allow simultaneous read and write operations to the file
1. Parameter filename: Name of the file.
2, Parameter mode: ' R ' (read), ' W ' (write), ' a ' (append).
3, parameter bufsize: If 0 is not buffered, if 1 is a row buffer, if it is a number greater than 1 indicates the size of the buffer.
Input ([prompt]) Get user input
It is recommended to use raw_input because the function will not capture the user's error input
Open (name[, mode[, Buffering]) Open File
What is the difference from file? Recommended use of Open
Print Print function
Raw_input ([prompt]) Set input, input is handled as String

Vi. Other

Help ()--Information

Vii. PostScript

Built-in functions, generally because the use of frequency is more frequent or meta-operation, so through the form of built-in functions provided, through the Python built-in function classification analysis can be seen: basic data operations are basically some mathematical operations (except subtraction), logical operations, set operations, basic IO operations , and then it is the reflection of the language itself, but also the operation of the string, is also more commonly used, especially the need to pay attention to the reflection operation.

Python built-in functions Daquan (category)

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