How to pass a variable as an argument to a function if the variable exists

Question

I want to use a function and pass an argument to it whether a variable exists. If the variable does not exist, then I want to use the function with the default value of the argument.

So far my code looks like this:

if transformation:
    '''
    If there is a computed transformation
    take it as an initial value.
    '''
    transformation = o3d.pipelines.registration.registration_icp(source,
                                                                    target,
                                                                    max_cor_dist,
                                                                    transformation).transformation
else:
    '''
    If there is not a computed transformation
    do not take an initial value.
    '''
    transformation = o3d.pipelines.registration.registration_icp(source,
                                                                    target,
                                                                    max_cor_dist).transformation

I feel like there is a better way to write this, any suggestions ?

What’s the default value if you don’t pass the argument? — deceze, Dec 09 '22 at 09:00
@deceze sorry for not clarifying that. The default value is an identity matrix, of type numpy array with shape 4x4. Here is the [link](http://www.open3d.org/docs/latest/python_api/open3d.pipelines.registration.registration_icp.html#open3d-pipelines-registration-registration-icp) to the function I want to use in case anyone wants that. — mkr, Dec 09 '22 at 09:04

score 2 · Answer 1 · answered Dec 09 '22 at 09:05

You can construct just the different arguments to be passed and then use argument unpacking, like this

args = (source, target, max_cor_dist, transformation) if transformation \
    else (source, target, max_cor_dist)
o3d.pipelines.registration.registration_icp(*args).transformation

matszwecja · Accepted Answer · 2022-12-09T09:42:59.507

2

args = [source, target, max_cor_dist]
if transformation:
    args.append(transformation) 
transformation = o3d...registration_icp(*args).transformation

edited Dec 09 '22 at 09:42

answered Dec 09 '22 at 09:05

matszwecja

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How to pass a variable as an argument to a function if the variable exists

2 Answers2