CODEWITHSUNDEEP
pythonvariablesglobal
flying_fluid_four
flying_fluid_four

Reputation: 764

Refer python variables using two other variables

I have fixed variables :

apple_weight = 50
mango_weight = 100
veggie1 = apple
veggie2 = mango

I want to be able to refer the weight variables by using the veggie variables in my code :

whatcomeshere = globals()[[str(veggie1) + str(_weight)]]

print("The weight of the veggie {}, is {}").format(veggie1, whatcomeshere)

I am trying to use the globals statement as above but get the following error:

Traceback (most recent call last):

  File "<ipython-input-9-bceaa9070b38>", line 3, in <module>
    veggie1 = apple

NameError: name 'apple' is not defined

Upvotes: 0

Views: 39

Answers (2)

Garrigan Stafford
Garrigan Stafford

Reputation: 1403

The error you are receiving is because the name apple is not declared or defined before referencing it in the line veggie1. I assume you want veggie1 to be the string apple so you would need to

veggie1 = "apple"

For the issue of refering to other variables, you can't directly build the names of variables like you are in

[str(veggie1) + str(_weight)]

Edit: skullgoblet1089's Answer shows a good way to use a dictionary to do what you are doing

What this will return is [apple50] which is I presume is not what you want. You need to explicitly call apple_weight.

If you want to generate variable names you would want to use a dictionary and then generate strings as keys for the dictionary.

https://www.w3schools.com/python/python_dictionaries.asp

Upvotes: 0

skullgoblet1089
skullgoblet1089

Reputation: 614

apple and mango are interpreted as variables that do not exist. You mean to define them as string literals. See below:

apple_weight = 50
mango_weight = 100
veggie1 = 'apple'
veggie2 = 'mango'

You might find it easier to use a simple data type like a dictionary to encapsulate this structure rather than finagling the global namespace.

APPLE_CDE = 'apple'
MANGO_CDE = 'mango'
d = {
  APPLE_CDE: {'weight': 50},
  MANGO_CDE: {'weight': 100}
}
w = d.get(APPLE_CDE, {}).get('weight', None)
print(w)

Upvotes: 2

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