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python - 如何搜索以列表为值的字典？

问题描述

这是我的作业题，题目给了我一本字典，让我在字典里搜索。这是字典：

{"childrens": [
    ["Be Our Guest", "Angela Lansbury", 224, 0],
    ["Lullabye", "Billy Joel", 213, 0]],
"dance": [
    ["Happy Now", "Kygo", 211, 0],
    ["Grapevine", "Tiesto", 150, 0],
    ["Headspace", "Dee Montero", 271, 0]],
"blues": [
    ["Dream of Nothing", "Bob Margolin", 208, 0]
    ["Rock and Stick", "Boz Scaggs", 290, 0],
    ["At Last", "Etta James", 181, 0],
    ["You’re Driving Me Crazy", "Van Morrison", 286, 0]],
"kpop": [
    ["Not That Type", "gugudan", 191, 0],
    ["IDOL", "BTS", 222, 0],
    ["Believe Me", "Seo In Young", 191, 0],
    ["Baam", "MOMOLAND", 208, 0],
    ["Hide Out", "Sultan of the Disco", 257, 0]]
}

键是“儿童”、“舞蹈”、“布鲁斯”和“kpop”。但问题是值列表包含多个元素。有整数类型和字符串类型。值列表中的第一项是歌曲名称，第二项是艺术家的姓名。所以我被要求通过字典搜索艺术家并返回歌曲。下面是我的代码。

def getSongsByArtist(library, artist):
value = []
value = library.values()
result = []
for sublist in value:
    for item in sublist:
        if item == artist:
            result.append(sublist[0])
return result

我应该得到“终于”作为输出，但由于某种原因，我的输出是“空无一物”，我不知道为什么。

标签： pythonlistdictionary

解决方案

您可以尝试使用此单线：

def getSongsByArtist(library, artist):
    return [s[0] for l in library.values() for s in l if s[1] == artist]

或以另一种形式：

def getSongsByArtist(library, artist):
    # Set up return list
    rv = []
    # Loop over lists of lists in dictionary values
    for l in library.values():
        # For each sublist:
        for s in l:
            # if the artist is correct
            if s[1] == artist:
                # append the track to the return list
                rv.append(s[0])
    return rv

用法：

>>> getSongsByArtist(library, 'Billy Joel')
['Lullabye']

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