一个值的Python Dictionary索引 [英] Python Dictionary index of a value

问题描述

我正在尝试从字典获取一个值的索引，并且不确定要尝试什么。

I am currently trying to get the index of a value from a dictionary and unsure what to try.

我的字典是：

    midi2notes = {                                  
        'c':("0","12","24","36","48","60","72","84","96","108","120"),
        'des':("1","13","25","37","49","61","73","85","97","109","121"),
        'd':("2","14","26","38","50","62","74","86","98","110","122"),
        'ees':("3","15","27","39","51","63","75","87","99","111","123"),
        'e':("4","16","28","40","52","64","76","88","100","112","124"),
        'f':("5","17","29","41","53","65","77","89","101","113","125"),
        'ges':("6","18","30","42","54","66","78","90","102","114","126"),
        'g':("7","19","31","43","55","67","79","91","103","115","127"),
        'aes':("8","20","32","44","56","68","80","92","104","116"),
        'a':("9","21","33","45","57","69","81","93","105","117"),
        'bes':("10","22","34","46","58","70","82","94","106","118"),
        'b':("11","23","35","47","59","71","83","95","107","119")
    }

示例：我想获取值 - 从键'c'的60。哪个应该是5.最有效/最快速的方法是什么。

Example: I want to get the index of value-"60" from key- 'c'. Which should be 5. What would be the most efficient/quickest way to go about this.

推荐答案

我会做： p>

I would do:

midi2notes['c'].index('60')

如果没有找到索引，这将引发 ValueError ，但是如果数字通常在元组中，这将很难击败优化的C后端。

This will raise an ValueError if the index isn't found, but if the numbers are usually in the tuple, it'll be hard to beat the optimized C backend.

>>> midi2notes = {                                  
...         'c':("0","12","24","36","48","60","72","84","96","108","120"),
...         'des':("1","13","25","37","49","61","73","85","97","109","121"),
...         'd':("2","14","26","38","50","62","74","86","98","110","122"),
...         'ees':("3","15","27","39","51","63","75","87","99","111","123"),
...         'e':("4","16","28","40","52","64","76","88","100","112","124"),
...         'f':("5","17","29","41","53","65","77","89","101","113","125"),
...         'ges':("6","18","30","42","54","66","78","90","102","114","126"),
...         'g':("7","19","31","43","55","67","79","91","103","115","127"),
...         'aes':("8","20","32","44","56","68","80","92","104","116"),
...         'a':("9","21","33","45","57","69","81","93","105","117"),
...         'bes':("10","22","34","46","58","70","82","94","106","118"),
...         'b':("11","23","35","47","59","71","83","95","107","119")
...     }
>>> midi2notes['c'].index('60')
5
>>> midi2notes['c'].index('180')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: tuple.index(x): x not in tuple
>>> 

这篇关于一个值的Python Dictionary索引的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！