在python中的字典中的列表中附加值答案

【问题标题】：Appending values in a list in a dictionary in python在python中的字典中的列表中附加值
【发布时间】：2019-11-07 06:37:35
【问题描述】：

我正在尝试将值添加到字典内的列表中。我查看了this 并尝试了append，但出现错误。

代码：

def name_counts(x):
    firsts = {}
    for full in x:
        part = full.split()
        fn = part[0]
        if fn in firsts:
            firsts[fn].append(full)
        else:
            firsts[fn] = []
            firsts[fn] = full
    return(firsts)


name_list = ["David Joyner", "David Zuber", "Brenton Joyner",
             "Brenton Zuber", "Nicol Barthel", "Shelba Barthel",
             "Shelba Crowley", "Shelba Fernald", "Shelba Odle",
             "Shelba Fry", "Maren Fry"]
print(name_counts(name_list))

错误：

AttributeError: 'str' 对象没有属性 'append'

期望的输出：

{'Shelba': ['Shelba Barthel', 'Shelba Crowley', 'Shelba Fernald', 'Shelba Odle', 'Shelba Fry'],'David': ['David Joyner', 'David Zuber'], 'Brenton': ['Brenton Joyner', 'Brenton Zuber'], 'Maren': ['Maren Fry'], 'Nicol': ['Nicol Barthel']}

【问题讨论】：

firsts[fn] = full ...?
试试firsts[fn] =full，因为firsts是一本字典。
@ArkistarvhKltzuonstev “尝试”是什么意思？那行是问题。
似乎是 defaultdict 的一个很好的用例

标签： python list dictionary append

【解决方案1】：

def name_counts(x):
firsts = {}
for full in x:
    part = full.split()
    fn = part[0]
    if fn not in firsts:
        firsts[fn] = []

    firsts[fn].append(full)
return(firsts)


name_list = ["David Joyner", "David Zuber", "Brenton Joyner",
         "Brenton Zuber", "Nicol Barthel", "Shelba Barthel",
         "Shelba Crowley", "Shelba Fernald", "Shelba Odle",
         "Shelba Fry", "Maren Fry"]
print(name_counts(name_list))

【讨论】：

【解决方案2】：

当您创建列表时，您会立即将其替换为字符串。试试：

if fn in firsts:
    firsts[fn].append(full)
else:
    firsts[fn] = [full]

而不是

if fn in firsts:
    firsts[fn].append(full)
else:
    firsts[fn] = []
    firsts[fn] = full

【讨论】：