Dynamically naming list in python3

Question

I want to dynamically name the list and use that,I searched a lot but did not get the satisfactory answers how to do that.

if __name__=="__main__":

    lst_2017=[]
    lst_2018=[]
    lst_2019=[]


    for year in range(2017,2020):
        #avg_data is function which returns a list of number
        lst_"{}".format(year) = avg_data()

Error:

 File "<ipython-input-84-4c1fefedd83e>", line 9
    lst_"{}".format(year) = avg_data()
           ^
 SyntaxError: invalid syntax

Expected :

loop will iterate 3 times and function return the 3 list in the respective lists

example:

 lst_2017=[1,2,4]
 lst_2018=[3,4,5]
 lst_2019=[3,4,6]

There's no need to create dynamically named variables. It is not useful. Consider using a dictionary instead. — khelwood
– khelwood, Commented May 16, 2020 at 20:06

RoadRunner · Accepted Answer · 2020-05-16 20:38:55Z

4

Use a dictionary instead of naming multiple dynamic variables. Then all your data is in one data structure and easily accessible from key/value pairs.

For the below example I simply zip up the years and data together to construct a dictionary, where years are the keys and averages are the values.

avg_data = [[1,2,4], [3,4,5], [3,4,6]]

result = {}
for year, avg in zip(range(2017, 2020), avg_data):
    result[year] = avg

print(result)

Which can also be done like this, since zip(range(2017, 2020), avg_data) will give us (year, avg) tuples, which can be directly translated to our desired dictionary using dict():

result = dict(zip(range(2017, 2020), avg_data))

print(result)

Output:

{2017: [1, 2, 4], 2018: [3, 4, 5], 2019: [3, 4, 6]}

You'll probably have to tweak the above to get your desired result, but it shows the general idea.

edited May 16, 2020 at 20:38

answered May 16, 2020 at 20:16

RoadRunner

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Comments

Alchimie · Accepted Answer · 2020-05-17 03:06:40Z

2

Use dictionary with iter:

avg_data = [[1,2,4], [3,4,5], [3,4,6]] 
it=iter(avg_data)
d={}
for i in range(2017,2020):
    d["lst_"+str(i)]=next(it,None)

for k in d.keys():
    print(k, "=",d[k])

answered May 17, 2020 at 3:06

Alchimie

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