How to use the concept of indexing dictionary in python [duplicate] - python

This question already has answers here:
Append a dictionary to a dictionary [duplicate]
(7 answers)
How to index into a dictionary?
(11 answers)
Closed 2 months ago.
I encountered a program where I had to append one dictionary into another, and I was unable to do it because I could not use indexing in dictionary so I wanted to know what the possible ways are I could do it

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creating a list from a set modifies the order of the numbers [duplicate]

This question already has answers here:
python order of elements in set
(2 answers)
Why is the order in dictionaries and sets arbitrary?
(5 answers)
Closed 26 days ago.
I have a list a:
a={4941, 4980, 3855, 4763, 4955}
I convert into a list:
b=list(a)
b now becomes [4980, 4955, 4763, 4941, 3855]
Sorry am I missing something? Eventhough set is an unordered structure why should it change the order ? Or is it the list function that is doing this?
Sorry if this is too naive a question! Many thanks.

Sorted function for tuple in python [duplicate]

This question already has answers here:
Python .sort() not working as expected
(8 answers)
How to sort a list of strings numerically?
(14 answers)
Closed last year.
p=('99','655','864','654')
e=sorted(p)
the result is ['654', '655', '864', '99']
why is 99 at last? It should be first.

Selecting a List Inside a List in Python [duplicate]

This question already has answers here:
Access item in a list of lists
(8 answers)
Closed 1 year ago.
stats=[[5,1,4],[3,4,3],[2,3,5]]
I was just wondering how I would select an element and I can't find anything that will help. for example, how would I select the 2 in the last set of numbers
its called 2 dimensional list and below is the way. thanks
stats[2][0]

I'm trying to append to a list in python but it gives back a NoneType [duplicate]

This question already has answers here:
Why does "x = x.append(...)" not work in a for loop?
(8 answers)
Closed 2 years ago.
This is my code but my output gives a none type back and not a list full of numbers.
PHC=[]
for i in range(len(df)):
x=df['HC'][0:i+1].mean()
PHC=PHC.append(x)
len[df]['HC']
instead of
len[df]

Python :error'list' object has no attribute 'sorted' [duplicate]

This question already has answers here:
Python list sort in descending order
(6 answers)
Closed 5 years ago.
This is my code:
#这是一个有关旅行的程序
place=['北京天安门','西安兵马俑','香港游乐园','日本秋叶原']
print(place)
print(sorted(place))
print(place)
place.sorted(reverse=true)
print(place)
When I run my code, something Wrong happens.
place.sorted(reverse=true)
or
sorted(place)
Using the 2nd way, how can I give (reverse=true)?
Just use sorted(place, reverse=True).

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