I am trying to understand the class L and in particular its method .attrgot(). I am working through lecture 2, the bears example.
I have read the docs and understand that L is a fastai class that is basically a modified list. I also understand that .attrgot() creates a new instance of L that contains the attributes specified in the method. But the example uses results.attrgot('content_url'). It’s the “content_url” that is confusing me. That string does not appear in results. Where does this string come from and what is it matching with?
Hi I have had similar problems trying to get the chapter 2 example to work. I get different error messages every time I run it. I know I got it to work once, but I haven’t gotten it to work since.
Why does it do something different every time I run it? Is this a common issue?
@Mark and @msivanes just checked out the ImageObject Class of Azure, the attribute is ‘ContentUrl’, not ‘content_url’. How did it end up as ‘content_url’ in the notebook?
Hi, @mariasimon. It’s been a while since I’ve looked at this. Looking at the docs, you seem to be right.
I don’t have an answer to your question, and I don’t use Azure enough to spend the time to try to figure it out. My guess is that something is generating a dictionary, and that .attrgot() is accessing that dictionary with ‘content_url’ as the key. In this case, it’s not invoking the object attribute directly, but a dictionary that is somehow generated. But it’s just a guess. You can try playing with the results object see what you can find.
Sorry that I’m not more help.
Added: Try results['content_url'] and if it returns anything; if it does, a dictionary must exist.
results is itself from L class. It is similar to a list of dictionaries. print(results) will show you the elements. It has a particular key: ‘contentUrl’. So results.attrgot(‘contentUrl’) will return all the dictionaries with the key ‘contentUrl’.
Honestly, I don’t remember this that well, and haven’t looked in months. But the reason there is a dictionary with the key ‘contentUrl’ is presumably that the Azure api put it there. That’s what I was trying to say. ‘contentUrl’ as a key is not from fastai, it’s from Azure. The L class is a fastai class.
As pointed out, it does not match ‘content_url’ in the notebook.
Yeah, I ran into this same exact problem. Has this been updated? Doesn’t look like it in the most recent version of the notebooks for this lecture (as far as I’ve seen).
