CODEWITHSUNDEEP
pythonpython-3.xdictionaryfor-loopattributeerror
David Hicks
David Hicks

Reputation: 11

Attribute Error within a for loop? will not return key as attribute

I have tried converting key to a string or reassigning key to another variable. Key will return an attribute within sample, but key is not being seen as sample_name...

for key in samples[1].__dict__:
    print(key)
    for row in samples:
        print(row.key)

Output:
sample_name
Traceback (most recent call last):
print(row.key)
AttributeError: 'sample' object has no attribute 'key'

Upvotes: 0

Views: 829

Answers (3)

viveksyngh
viveksyngh

Reputation: 787

Try to see if the following code helps you:

for key in samples[1].__dict__:
    print(key)
    for row in samples:
        print getattr(row, key)

Upvotes: 0

David Chou
David Chou

Reputation: 46

Well, i've spent a little time to figure out what you want.

samples is a list. Each object in list samples is a class instance with few attribute. And you want to output their value of each attribute?

If I'm right you may try

for each in samples:
    for key in each.__dict__:
        try:
            print(each.key)
        except AttributeError, Argument:
            print('AttributeError')
            print(Argument)

However I don't think it's a good idea to use __dict__. Give more info about you problem might help us provide more useful suggestions.

Upvotes: 0

Jared Goguen
Jared Goguen

Reputation: 9010

When you do row.key, you are trying to look up the 'key' attribute on row. This is equivalent to doing getattr(row, 'key'). Since row has no 'key' attribute, this produces an error. To dynamically look up an attribute when you have a string for the attribute name, use getattr(row, key) and since key = 'sample_name', this is equivalent to getattr(row, 'sample_name'). Notice the lack of quotes around key in the first usage.

Upvotes: 1

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