江西建设门户网站,苍梧县网站建设,专业建设计划,做网站如何收集资料在 Python 中#xff0c;列表和字典都是基础数据类型#xff0c;这两种数据类型会通过相互嵌套和多个层级形成复杂的数据类型#xff0c;类似 JSON 数据格式#xff0c;对列表和字典排序其实可以类比是对 JSON 排序。
列表排序
列表可以使用 sorted() 函数排序#xff1…在 Python 中列表和字典都是基础数据类型这两种数据类型会通过相互嵌套和多个层级形成复杂的数据类型类似 JSON 数据格式对列表和字典排序其实可以类比是对 JSON 排序。
列表排序
列表可以使用 sorted() 函数排序
In [1]: color [White, Black, Red, Yellow, Green, Blue]In [2]: sorted(color)
Out[2]: [Black, Blue, Green, Red, White, Yellow]对列表降序排序
In [3]: sorted(color, reverseTrue)
Out[3]: [Yellow, White, Red, Green, Blue, Black]也可以使用列表内置的排序属性 list.sort()
In [1]: color [White, Black, Red, Yellow, Green, Blue]In [2]: color
Out[2]: [White, Black, Red, Yellow, Green, Blue]In [3]: color.sort()In [4]: color
Out[4]: [Black, Blue, Green, Red, White, Yellow]In [5]: color.sort(reverseTrue)In [6]: color
Out[6]: [Yellow, White, Red, Green, Blue, Black]list.sort() 只有列表才有的属性它会直接修改原列表并返回 None原地排序。而 sorted() 适用于任何可迭代的对象如果你不需要原地排序使用 sorted() 会更加方便和高效。 字典排序
字典使用 sorted() 函数排序
In [1]: color {White: 1, Black: 2, Red: 3, Yellow: 3, Green: 2, Blue: 1}In [2]: color
Out[2]: {White: 1, Black: 2, Red: 3, Yellow: 3, Green: 2, Blue: 1}对字典的键升序排序
In [3]: sorted(color)
Out[3]: [Black, Blue, Green, Red, White, Yellow]sorted() 函数默认对字典的键升序排序等同如下形式
In [4]: sorted(color.keys(), reverseFalse)
Out[4]: [Black, Blue, Green, Red, White, Yellow]对字典的键降序排序
In [5]: sorted(color, reverseTrue)
Out[5]: [Yellow, White, Red, Green, Blue, Black]In [6]: sorted(color.keys(), reverseTrue)
Out[6]: [Yellow, White, Red, Green, Blue, Black]对字典的值升序排序
In [7]: sorted(color.values())
Out[7]: [1, 1, 2, 2, 3, 3]这种排序结果是字典值的列表所以一般情况下需要指定排序算法通常使用 lambda 函数作为排序规则。 在 lambda x: x[1] 中 x 是元组x[0] 是键x[1] 是值。 In [8]: sorted(color.items(), keylambda x: x[1])
Out[8]:
[(White, 1),(Blue, 1),(Black, 2),(Green, 2),(Red, 3),(Yellow, 3)]字典排序完成后可以通过 dict() 函数将元组变回字典
In [15]: dict(sorted(color.items(), keylambda x: x[1]))
Out[15]: {White: 1, Blue: 1, Black: 2, Green: 2, Red: 3, Yellow: 3}在 Python 3.5含以前字典是不能保证顺序的键值对 A 先插入字典键值对 B 后插入字典但是当你打印字典的 Keys 列表时你会发现 B 可能在A的前面。 但是从 Python 3.6 开始字典是变成有顺序的了。 嵌套排序
上文只是对列表和字段排序进行单独的说明但是在实际开发过程中嵌套排序才是经常遇到的所以嵌套排序才是本文的重点。
通过排列组合可知嵌套排序有如下四种
字典嵌套字典
In [1]: color {...: White: {level: 1},...: Black: {level: 2},...: Red: {level: 3},...: Yellow: {level: 3},...: Green: {level: 2},...: Blue: {level: 1}...: }In [2]: color
Out[2]:
{White: {level: 1},Black: {level: 2},Red: {level: 3},Yellow: {level: 3},Green: {level: 2},Blue: {level: 1}}对字典的键升序排序
In [3]: sorted(color.items())
Out[3]:
[(Black, {level: 2}),(Blue, {level: 1}),(Green, {level: 2}),(Red, {level: 3}),(White, {level: 1}),(Yellow, {level: 3})]In [4]: dict(sorted(color.items()))
Out[4]:
{Black: {level: 2},Blue: {level: 1},Green: {level: 2},Red: {level: 3},White: {level: 1},Yellow: {level: 3}}
对字典的键降序排序
In [5]: sorted(color.items(), keylambda x: x[0], reverseTrue)
Out[5]:
[(Yellow, {level: 3}),(White, {level: 1}),(Red, {level: 3}),(Green, {level: 2}),(Blue, {level: 1}),(Black, {level: 2})]In [6]: dict(sorted(color.items(), keylambda x: x[0], reverseTrue))
Out[6]:
{Yellow: {level: 3},White: {level: 1},Red: {level: 3},Green: {level: 2},Blue: {level: 1},Black: {level: 2}}字典嵌套列表
In [1]: color {...: White: [250, 255, 251],...: Black: [0, 2, 1],...: Red: [255, 2, 0],...: Yellow: [255, 254, 0],...: Green: [1, 128, 0],...: Blue: [0, 1, 255]...: }In [2]: color
Out[2]:
{White: [250, 255, 251],Black: [0, 2, 1],Red: [255, 2, 0],Yellow: [255, 254, 0],Green: [1, 128, 0],Blue: [0, 1, 255]}对字典的键升序排序
In [3]: sorted(color.items())
Out[3]:
[(Black, [0, 2, 1]),(Blue, [0, 1, 255]),(Green, [1, 128, 0]),(Red, [255, 2, 0]),(White, [250, 255, 251]),(Yellow, [255, 254, 0])]In [4]: dict(sorted(color.items()))
Out[4]:
{Black: [0, 2, 1],Blue: [0, 1, 255],Green: [1, 128, 0],Red: [255, 2, 0],White: [250, 255, 251],Yellow: [255, 254, 0]}对字典中列表的值升序排序
In [5]: sorted(color.items(), keylambda x: x[1][0])
Out[5]:
[(Black, [0, 2, 1]),(Blue, [0, 1, 255]),(Green, [1, 128, 0]),(White, [250, 255, 251]),(Red, [255, 2, 0]),(Yellow, [255, 254, 0])]In [6]: sorted(color.items(), keylambda x: x[1][1])
Out[6]:
[(Blue, [0, 1, 255]),(Black, [0, 2, 1]),(Red, [255, 2, 0]),(Green, [1, 128, 0]),(Yellow, [255, 254, 0]),(White, [250, 255, 251])]In [7]: sorted(color.items(), keylambda x: x[1][2])
Out[7]:
[(Red, [255, 2, 0]),(Yellow, [255, 254, 0]),(Green, [1, 128, 0]),(Black, [0, 2, 1]),(White, [250, 255, 251]),(Blue, [0, 1, 255])]在 lambda x: x[1][0] 中x[1][0] 代表按列表第一个值排序以此类推。 对字典中列表的值降序排序
In [8]: sorted(color.items(), keylambda x: x[1][0], reverseTrue)
Out[8]:
[(Red, [255, 2, 0]),(Yellow, [255, 254, 0]),(White, [250, 255, 251]),(Green, [1, 128, 0]),(Black, [0, 2, 1]),(Blue, [0, 1, 255])]列表嵌套列表
In [1]: color [[White, 2], [Black, 3], [Red, 4],[White, 1], [Black, 2], [Red, 3]]In [2]: color
Out[2]:
[[White, 2],[Black, 3],[Red, 4],[White, 1],[Black, 2],[Red, 3]]In [3]: sorted(color)
Out[3]:
[[Black, 2],[Black, 3],[Red, 3],[Red, 4],[White, 1],[White, 2]]In [4]: sorted(color, reverseTrue)
Out[4]:
[[White, 2],[White, 1],[Red, 4],[Red, 3],[Black, 3],[Black, 2]]列表嵌套字典
In [1]: colors [...: {color: White, level: 2},...: {color: Black, level: 3},...: {color: Red, level: 4},...: {color: White, level: 1},...: {color: Black, level: 2},...: {color: Red, level: 3}...: ]In [2]: colors
Out[2]:
[{color: White, level: 2},{color: Black, level: 3},{color: Red, level: 4},{color: White, level: 1},{color: Black, level: 2},{color: Red, level: 3}]对列表中每个字典的 color 字段进行排序单级排序
In [3]: sorted(colors, keylambda x: x[color])
Out[3]:
[{color: Black, level: 3},{color: Black, level: 2},{color: Red, level: 4},{color: Red, level: 3},{color: White, level: 2},{color: White, level: 1}]对列表中每个字典的 color 字段进行排序后再对 level 字段排序多级排序
In [4]: sorted(colors, keylambda x: (x[color], x[level]))
Out[4]:
[{color: Black, level: 2},{color: Black, level: 3},{color: Red, level: 3},{color: Red, level: 4},{color: White, level: 1},{color: White, level: 2}]参考文章 https://docs.python.org/zh-cn/3/howto/sorting.html https://www.kingname.info/2019/07/13/python-dict https://blog.csdn.net/ray_up/article/details/42084863
