Python multiple elif alternatives

Question

I have a script which needs to iterate through thousands of various different, but simple options.

I can use if...elif to iterate through them, but am wondering if there is a faster / better option than thousands of elifs. For example

if something == 'a':
    do_something_a
elif something == 'b':
    do_something_b
elif something == 'c':
    do_something_c
elif something == 'd':
    do_something_d
...
A thousand more elifs
...
else:
    do_something_else

The thing I will be doing will usually be running a function of some kind.

It depends on where `something` comes from. Is it user input of some kind? — melpomene, Sep 12 '18 at 10:38
It would be a variable value, generally taken from a column in a database which I am iterating through. — Mike de H, Sep 12 '18 at 10:39

score 4 · Answer 1 · answered Sep 12 '18 at 10:42

4

you can use a dictionary to control mutliple possible logical paths:

def follow_process_a():
   print('following a')

def follow_process_b():
   print('following b')

keyword_function_mapper = 
{'a' : follow_process_a ,
 'b' : follow_process_b,                     
}

current_keyword = 'a'
run_method = keyword_function_mapper[current_keyword]
run_method()

answered Sep 12 '18 at 10:42

matyas

2,696
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Exactly what I needed. Thanks! – Mike de H Sep 12 '18 at 10:48
you are welcome! If you want you can also mark this answer as accepted answer if it was what you were looking for. – matyas Sep 12 '18 at 10:50

Dmytro Huz · Answer 2 · 2019-06-18T14:55:24.187

1

you can use a dictionary for that in this way:

def do_something_a():
    print 1

def do_something_b():
    print 2

dict = {'a': do_something_a, 'b': do_something_b}
dict.get(something)()

edited Jun 18 '19 at 14:55

answered Sep 12 '18 at 10:40

Dmytro Huz

1,514
2
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thank you, I fixed `;` I expected that do_something_a() function is already exist. so this code will call it if something == a – Dmytro Huz Sep 12 '18 at 11:04
@melpomene thank you that showed me that. you are absolutely right. I fixed it in my answer. – Dmytro Huz Sep 12 '18 at 11:11

score 0 · Answer 3 · answered Sep 12 '18 at 10:41

What I would recommend is to create a dictionary which maps the somethings to their respective function. Then you can apply this dictionary to the data.

More information: https://jaxenter.com/implement-switch-case-statement-python-138315.html (Dictionary Mapping)

Python multiple elif alternatives

3 Answers3