在Python函数中返回多个列表

Question

我是Python的新手,我正在尝试创建一个函数,该函数使用来自用户输入的不同材料参数创建列表,如下面的代码所示.

def material():
    layers = int(raw_input("State the number of material layers in the wall (0 for default material): "))

    rho = [] # Density [kg/m3]
    c = [] # Heat capacity [J/(kg K)] 
    k = [] # Heat conductivity [W/(m K)]
    #a = [] # Thermal diffusivity [m2/s]
    d = [] # Thickness of material [m]

    # Saveing material properties
    if layers == 0:
        rho.append(2300)
        c.append(900)
        k.append(1.6)
        d.append(3.2)
        layers = 1

    else:
        for i in range(layers):
            print "\n" "Define thermal properties for material", i+1,"(starting from left)"
            rho.append(float(raw_input("Density [kg/m3]: ")))
            c.append(float(raw_input("Heat capacity [J/(kg K)]: ")))
            k.append(float(raw_input("Heat conductivity [W/(m K)]: ")))
            d.append(float(raw_input("Thickness [m]: ")))

    return ???

我应该如何返回rho,c,k,d和层,以便我能够打印 - 或者使用 - 例如d列表中的第二项？

print d[1]

Answer 1

我应该如何返回rho,c,k,d和层[...]？

只需这样做:

return rho, c, k, d, layers

然后你会称之为

rho, c, k, d, layers = material()
print d[1]

请注意,您返回的内容越多,您就越有可能将它们全部包装成某个结构(如dict(或namedtuple,或类等))

Answer 2

return 如果用逗号分隔它们,则可以返回多个值:

return rho, c, k, d, layers

这将使material返回包含一个元组rho,c,k,d,和layers.

完成此操作后,您可以material通过解压缩访问返回的值:

rho, c, k, d, layers = material()

这是一个演示:

>>> def func():
...     return [1, 2], [3, 4], [5, 6]
...
>>> a, b, c = func()
>>> a
[1, 2]
>>> b
[3, 4]
>>> c
[5, 6]
>>> a[1]
2
>>>