Check isnan function for empty strings

[ajdapretnar]

Bioinformatics Add-on often uses isnan to check for unknowns even in places, where one would expect string values. isnan fails for strings. Check whether these functions work and how. Fix the issue for empty strings accordingly.

Widgets that use isnan:

• OWFeatureSelection
• OWGeneInfo
• OWEnrichmentAnalysis
• OWKEGG
• OWSelectGenes

[cheral]

if the string contains a newline character, then it is not empty. Same goes for tabs, spaces and all forms of non-printable characters. We need to first strip the string and then check if the stripped string is empty.

isnan fails maybe because it uses number implementation , I think ...

how about using this function below ?

def isNotBlank (myString):
    if myString and myString.strip():
    #myString is not None AND myString is not empty or blank
        return True
    #myString is None OR myString is empty or blank
    return False

[kernc]

@cheral Strings are stripped in data loading stage. If the string is empty/not provided/strips to nothing, then it is represented as '' (an empty string). However, numpy.isnan() chokes on ''.