根据python中的字典值排序列表? [英] Sort a list based on dictionary values in python?
问题描述
我一直在尝试:
trial_dict = {'*':4,' - ':2,'+':3,'/':5}
trial_list = [' - ' ','+','/','+',' - ','*']
< >我去使用:
sorted(trial_list,key = trial_dict.values())
并得到:
TypeError: 'list'对象不可调用
然后我去创建一个可以使用 trial_dict.get()
:
def sort_help(x):
if isinstance(x,dict):
for i in x:
return x [i]
sorted(trial_list,key = trial_dict.get(sort_help(trial_dict) ))
我不认为 sort_help
功能对排序有任何影响。我不知道是否使用 trial_dict.get()
是正确的方法。
是 dict.get 是正确(或至少是最简单的)方式:
sorted(trial_list,key = trial_dict.get)
如Mark Amery所言,相当于明确的lambda:
$ p> sorted(trial_list,key = lambda x:trial_dict [x])
可能会更好,至少有两个原因:
- 排序表达式是可见的,可以立即编辑
- 它不会抑制错误(当列表包含不在dict中的东西时)。
Say I have a dictionary and then I have a list that contains the dictionary's keys. Is there a way to sort the list based off of the dictionaries values?
I have been trying this:
trial_dict = {'*':4, '-':2, '+':3, '/':5}
trial_list = ['-','-','+','/','+','-','*']
I went to use:
sorted(trial_list, key=trial_dict.values())
And got:
TypeError: 'list' object is not callable
Then I went to go create a function that could be called with trial_dict.get()
:
def sort_help(x):
if isinstance(x, dict):
for i in x:
return x[i]
sorted(trial_list, key=trial_dict.get(sort_help(trial_dict)))
I don't think the sort_help
function is having any affect on the sort though. I'm not sure if using trial_dict.get()
is the correct way to go about this either.
Yes dict.get is the correct (or at least, the simplest) way:
sorted(trial_list, key=trial_dict.get)
As Mark Amery commented, the equivalent explicit lambda:
sorted(trial_list, key=lambda x: trial_dict[x])
might be better, for at least two reasons:
- the sort expression is visible and immediately editable
- it doesn't suppress errors (when the list contains something that is not in the dict).
这篇关于根据python中的字典值排序列表?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!