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How can I create a list of variables in python. for example how can I create the following variables f_1, f_2, f_3, ..., f_100. I want to make them with 'for' loop. is there a function that I can use in this specific problem?

mehrdad kolivand
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  • Is there any particular reason why you want to create many separately named variables, rather than just use a list object (e.g. `f`) that you then index by number (e.g. `f[3]`)? – alani Jun 06 '20 at 07:37
  • Take a look at https://stackoverflow.com/questions/961632/converting-integer-to-string – mushishi Jun 06 '20 at 07:38

4 Answers4

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how about a dictionary?

numd = {}
for i in range(100):
    numd["f_{}".(i)] = 0

or just make a list then add the values there with a for loop

rn0mandap
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Using map and range; coercing integers to strings in the lambda function and prefixing the numeric with "f_": 

[*map(lambda x: "f_"+str(x), [*range(1, 100)])]

Using a for loop: 

numeric_range = [*range(1, 100)]
lst = []
for i in numeric_range:
    lst.append("f_"+str(i))
print(lst)

Using a list comprehension: 

["f_"+str(i) for i in range(1, 100)]
hello_friend
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0

If you really want to assign new variables dynamically, you could run an assignment command via the exec function, for example:

for i in range(100):
    value = i * 2
    var_name = "f_{}".format(i)
    exec("{} = {}".format(var_name, repr(value)))

print(f_30)

However, you would need a very strong and specific reason to want to do the above.

The normal expectation would be that you simply put the values into a single list object, and access it by index number. For example:

f = []
for i in range(100):
    value = i * 2
    f.append(value)

print(f[30])
alani
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0

If you are ok with it that they are created in the global namespace then you could also use the following code: 

for i in range(100):
    globals()["f_"+str(i)] = 0

globals() gets you a dictionary of the names defined in the global namespace.

podestplatz
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