On Sunday, 31 October 2021, MRAB <pyt...@mrabarnett.plus.com> wrote: > 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. > > Please expand on how.
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