dynamically accesing variables in python

Question

Hello I am currently doing a project were I need up to 30.000 variables, which will be created dynamically. My problem however is accessing said variables dynamically , storing them in an array and accessing them like this works but I'd like to access them by name only. My code looks like:

NG=10
for i in range(1, NG+1 ):
    globals()[f"u_{i}"] = i
    print(u_{i})

Declaring variables like this works and they can be accessed by typing u_1, but the above print statement breaks the code. Is there an option to access a variable similar to this in python?

Dynamically creating variable name can be done using globals() which is error prone. Use dictionary for sanity of your code — jeff pentagon
– jeff pentagon, Commented Nov 9, 2021 at 14:39
For your example change the print statement to print(f'u_{i}') — jeff pentagon
– jeff pentagon, Commented Nov 9, 2021 at 14:41

Nite Block · Accepted Answer · 2021-11-09 14:37:45Z

2

You can access it the same way you set it:

globals()[f"u_{i}"]

Except I highly recommend you NOT to use global variables. You can use a dictionary; eg.

data = {}

data["some_key"] = 123
print(data["some_key"])

This will work the same way as does with global variables, except not having the pain of global variables.

answered Nov 9, 2021 at 14:37

Nite Block

2381 silver badge4 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Soothy · Accepted Answer · 2021-11-09 14:46:03Z

0

Using a Dictionary would be the best option if you ask me. Just to give an example of a dummy assignment:

import random
a={} # the dictionary
random.seed(5)
for i in range(30000):
  a['u'+str(i+1)]=random.random() # Or whatever value you want to put in the variable  
print(a['u1']) # First variable and so on...
print(a['u2'])

answered Nov 9, 2021 at 14:46

Soothy

347 bronze badges

2 Comments

Abbel Over a year ago

ok that might be more sensible, but how do I access those dynamically, like print(a[ 'ui' ])?

Soothy Over a year ago

Yes. You can either access them (if you just want to view) by print. If you want to use the variable somewhere, just reference as a['u1'] (or whatever term you need).

Collectives™ on Stack Overflow

dynamically accesing variables in python

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related