Data analysis with Python-2

Function

-If you want to reuse the same or very similar functions, write a function.
-function uses the DEF keyword declaration to return a value with the return keyword

def my_function(x, y, z=1.5):    if z > 1:        return z * (x + y)    else:        return z / (x + y)

-Returns None if no return at the end
-functions can have positional parameters and keyword arguments, keyword elaboration is usually used to specify default values or optional parameters, in the above code x and Y are positional parameters, and z is the keyword parameter, can be called in the following two methods

a = my_function(5,6,z=0.7)c = my_function(5,6,0.7)d = my_function(4,8)

-the keyword parameter must be located after the position parameter (if there is a positional parameter), you can specify the keyword parameter in any order
* Note: You can also pass positional parameters with keyword parameters. The previous example can be written as

 c = my_function(x=5,y=6,z=0.7)

namespaces, scopes, and local variables

-The function is happy to access the variables of two different scopes: global variable and local variable (local).
-python called namespaces
-The following function

def func():    a = []    for i in range(5):        a.append(i)

-After Func is called, the empty list A is created first, then 5 elements are added, and a is destroyed when the function exits
-If we define a as follows

a = []def func():    for i in range(5):        a.append(i)

-Although you can assign a global variable to a function, those variables must be declared as global variables with the GLOBALS keyword to

global a

Return multiple values

def f():    a = 5    b = 6     c = 7     return a,b,ca,b,c = f()print(a)print(b)print(c)

-The above code returns a ternary tuple
-You can also write the following code to return a dictionary

def f():    a = 5    b = 6     c = 7     return {"a":a,"b":b,"c":c}a= f()print(a)

Data analysis with Python-2