返回f字符串的For循环函数 [英] For loop function that returns f-string

问题描述

我是python的新手，正在尝试编写一个函数，该函数接受字典列表，并返回一个新的字符串列表，其中包含串联的每个字典中的名字和姓氏键.

I am new to python and trying to write a function that accepts a list of dictionaries and returns a new list of strings with the first and last name keys in each dictionary concatenated.

names = [{'first': 'John', 'last': 'Smith'}, {'first': 'Jessie', 'last': 'Snow'}]


 def name_function(lst):     
     for name in lst:       
         return f"{name['first']} {name['last']}" 

 names_function(names)
 'John Smith'

我编写了一个for循环，该循环遍历字典列表并返回一个f字符串，该字符串将每个字典中的名字和姓氏键连接在一起，但是，该循环无法在第一个键之外进行迭代，我希望有人可以指出我的问题.

I wrote a for loop that iterates thru the list of dictionaries and returns an f-string that concatenates first and last name keys in each dictionary, however, the loop fails to iterate beyond the first key and I am hoping some one can point me to the issue.

推荐答案

虽然有一个循环，但在循环中也有一个 return .在列表的第一次迭代中，此 return 将被命中并且函数的执行将在那里停止，仅返回该行的值(即字符串)，而不是预期的列表.

While you have a loop, you also have a return inside the loop. On the first iteration of the list this return will be hit and execution of the function will stop there, returning only value on that line — which is a string — rather than the list intended.

您要么需要在函数中添加一个列表以用作累加器，然后再返回—

You either need to add a list to the function to use as an accumulator before returning —

def names_function(lst):  
    names = []      
    for name in lst:       
        names.append(f"{name['first']} {name['last']}")
    return names   

或者使用列表理解

def names_function(lst):  
    return [f"{name['first']} {name['last']}" for name in lst]

names_function(names)

两者都会输出

['John Smith', 'Jessie Snow']

您还可以将 return 替换为 yield ，以将其转换为生成器.要获取所有值，您需要迭代生成器(或在其上调用 list )

You could also replace the return with a yield to turn this into a generator. To get all the values you would need to iterate the generator (or call list on it)

def names_function(lst):     
    for name in lst:       
        yield f"{name['first']} {name['last']}" 

list(names_function(names))

哪个给出相同的结果

['John Smith', 'Jessie Snow']

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