On 2021-10-31 17:25, Shaozhong SHI wrote:
I defined a function and apply it to a column in Pandas.  But it does not
return correct values.

I am trying to test which url in a column full of url to see which one can
be connected to or not

def connect(url):
     try:
         urllib.request.urlopen(url)
         return True
     except:
         return False

df['URL'] = df.apply(lambda x: connect(df['URL']), axis=1)

I ran without any error, but did not return any true.

I just could not find any error with it.

Can anyone try and find out why

You're passing a function to '.apply'. That has one argument,' x'.

But what is the function doing with that argument?

Nothing.

The function is just returning the result of connect(df['URL']).

df['URL'] is a column, so you're passing a column to '.urlopen', which, of course, it doesn't understand.

So 'connect' returns False.
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