Walrus operator definition:
a variable name followed by an expression or a value, this is a new assignment operator.
Here are three ways to use it:
1. For if else conditional expression
Basic writing:
x=5
if x<10:
print("hello fancy!")
Walrus operator writing:
if (x:=5) < 10:
print("hello fancy!")
operation result:
Two, for while loop
Basic writing:
num=3
while num:
print(f"{
num}")
num-=1
operation result:
Walrus operator writing:
num=3
while (num:=num-1)+1:
print(f"{
num}")
operation result:
Three, for derivation
Basic writing:
num1=[1,2,3,4,5]
count=1
def f(x):
global count
print(f"f(x)函数运行了{
count}次")
count+=1
return x**2
num2 = [f(x) for x in num1 if f(x) > 10 ]
print(num2)
Running result:
Written by walrus operator:
num1=[1,2,3,4,5]
count=1
def f(x):
global count
print(f"f(x)函数运行了{
count}次")
count+=1
return x**2
num2 = [n for x in num1 if ( n:= f(x) ) > 10 ]
print(num2)
operation result:
It can be seen that using the walrus operator can save function calls and improve performance.
Here f "f(x) function has been run {count} times" is a format conversion, if f is not added, this will happen:
