是的,它有,但它与C类似的编程语言不同(这是条件? value_if_true : value_if_false

在 Python 中,它如下: value_if_true 如果另一个条件值_if_false

例如: even_or_odd = “even” 如果 x % 2 == 0 其他 “odd”

如果否则版本可以写作如下:

sample_set="train" if "Train" in full_path else ("test" if "Test" in full_path else "validation")

模拟 Python Ternary 操作器。

例如

a, b, x, y = 1, 2, 'a greather than b', 'b greater than a'
result = (lambda:y, lambda:x)[a > b]()

出口:

'b greater than a'

你可能经常发现

cond and on_true or on_false

但这会导致一个问题,当 on_true == 0

>>> x = 0
>>> print x == 0 and 0 or 1
1
>>> x = 1
>>> print x == 0 and 0 or 1
1

在哪里你会期望这个结果为一个正常的特纳利运营商:

>>> x = 0
>>> print 0 if x == 0 else 1
0
>>> x = 1
>>> print 0 if x == 0 else 1
1

有多种方式,最简单的是在“印刷”方法中使用状态。

你可以使用

print("Twenty" if number == 20 else "Not twenty")

相当于:

if number == 20:
    print("Twenty")
else:
    print("Not twenty")

因此,可以打印超过两份声明,例如:

if number == 20:
    print("Twenty")
elif number < 20:
    print("Lesser")
elif 30 > number > 20:
    print("Between")
else:
    print("Greater")

可以写作如:

print("Twenty" if number == 20 else "Lesser" if number < 20 else "Between" if 30 > number > 20 else "Greater")

特纳利条件运营商简单地允许在单一线测试一个条件,取代多线,如果它使代码紧凑。

合成:

假如他是真實的,

1、使用Ternary Operator的简单方法:

# Program to demonstrate conditional operator
a, b = 10, 20
# Copy value of a in min if a < b else copy b
min = a if a < b else b
print(min)  # Output: 10

2、直接使用Tuples、词典和Lambda的方法:

# Python program to demonstrate ternary operator
a, b = 10, 20
# Use tuple for selecting an item
print( (b, a) [a < b] )
# Use Dictionary for selecting an item
print({True: a, False: b} [a < b])
# lambda is more efficient than above two methods
# because in lambda  we are assure that
# only one expression will be evaluated unlike in
# tuple and Dictionary
print((lambda: b, lambda: a)[a < b]()) # in output you should see three 10

3、管道运营商可以写作如下:

# Python program to demonstrate nested ternary operator
a, b = 10, 20
print ("Both a and b are equal" if a == b else "a is greater than b"
        if a > b else "b is greater than a")

上面的方法可以写作如:

# Python program to demonstrate nested ternary operator
a, b = 10, 20
if a != b:
    if a > b:
        print("a is greater than b")
    else:
        print("b is greater than a")
else:
    print("Both a and b are equal")
# Output: b is greater than a