了解为什么加入的工作方式有所不同
我希望进一步了解函数join（）使用format（）和列表时的工作方式不同。正如您可以在底部所说的那样，输出非常不同。
ina = "{a}{aa}{aaa}{aaaa}".format(a = "This ", aa = "is ", aaa = " my", aaaa = " house.")
print("=".join(ina))
list = "_".join(["Mayor in", "is the", "one to, done"])
print(list)
输出：
T=h=i=s= =i=s= = =m=y= =h=o=u=s=e=.
Mayor in_is the_one to, done
I would like some further insight in how the function join() works differently when using format(), and a list. As you can tell in the bottom, output is very different.
ina = "{a}{aa}{aaa}{aaaa}".format(a = "This ", aa = "is ", aaa = " my", aaaa = " house.")
print("=".join(ina))
list = "_".join(["Mayor in", "is the", "one to, done"])
print(list)
OUTPUT:
T=h=i=s= =i=s= = =m=y= =h=o=u=s=e=.
Mayor in_is the_one to, done
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ina现在是一个字符串：“这是我的房子”。将iTable
ina的每个元素（这是一个角色）获取，并使用=加入它。是一个清单。
将iTable
的每个元素[“市长”为“”，“一个”，“一个”，“完成”]，它是一个字符串，并使用_加入它。加入字符串（带有字符为元素）并加入列表（带有字符串作为元素）通常会给出不同的结果，除非您的列表恰好在其中有单个字符。
顺便说一句，在Python中使用
list作为变量名是一个不好的做法：list已经具有一个值。如果代码中的其他位置<代码>列表打算访问列表类型，则代码将失败。inais now a string:"This is my house".takes every element of the iterable
ina, which is a character, and joins it using=.is a list.
takes every element of the iterable
["Mayor in", "is the", "one to, done"], which is a string, and joins it using_.Joining a string (with character as elements) and joining a list (with strings as elements) will typically give different results, unless your list happens to have single characters in it.
As an aside, using
listas a variable name in Python is a bad practice:listalready has a value. Should some other place in code uselistintending to access the list type, the code would fail.这是因为字符串被存储为字符列表。在第一个示例中，ina =“这是我的房子”。在幕后存储为['t'，'h'，'i'，'s'，''，''，'y'，''，'，''，'h'等。 '='数组的每个元素之间给出了您看到的输出。
您拥有字符串列表（又称字符列表）的第二个示例被存储为[['m'，'a'，'y'，''，'o'，'r'，'，'，'，'i i' ，'n']，['i'，'s'，''，t'，'h'，'e']，['o'，...]]。 join（）仅在最外面的列表上运行，因此它仅在2个位置插入'_'。
您可以看到的一种方法是使用Len（）函数。
Len（Ina）是18岁，但是Len（[[“市长”，“是”，“一个to，完成”）是3。
This is because strings are stored as lists of characters. In the first example, ina = "This is my house." which behind the scenes is stored as ['T', 'h', 'i', 's', ' ', 'm', 'y', ' ', 'h', etc.], so join inserts the '=' between each element of the array giving the output you saw.
The second example where you have a list of strings (aka a list of lists of characters) is stored as [['M', 'a', 'y', 'o', 'r', ' ', 'i', 'n'], ['i', 's', ' ', t', 'h', 'e'], ['o', ...]]. join() only operates on the outermost list, so it will only insert '_' in 2 places.
One way you can see this is by using the len() function.
len(ina) would be 18, but len(["Mayor in", "is the", "one to, done"]) would be 3.