Python os path join on a list

Question

I can do   gt  gt  gt  os path join  c     home   foo   bar   some txt    c  home  foo  bar  some txt    But  when I do   gt  gt  gt  s    c   home foo bar some txt  split       gt  gt  gt  os path join s    c      home    foo    bar    some txt     What am I missing here

User · Answer

It s just the method  You re not missing anything  The official documentation shows that you can use list unpacking to supply several paths   s    c   home foo bar some txt  split      os path join  s    Note the  s intead of just s in os path join  s   Using the asterisk will trigger the unpacking of the list  which means that each list argument will be supplied to the function as a separate argument

User · Answer

The problem is  os path join doesn t take a list as argument  it has to be separate arguments   This is where    the  splat  operator comes into play     I can do   gt  gt  gt  s    c   home foo bar some txt  split       gt  gt  gt  os path join  s   c  home  foo  bar  some txt

User · Answer

This can be also thought of as a simple map reduce operation if you would like to think of it from a functional programming perspective   import os folders      home    vim     home   zathura     reduce lambda x y  os path join x y   each      for each in folders    reduce is builtin in Python 2 x  In Python 3 x it has been moved to itertools However the accepted the answer is better   This has been answered below but answering if you have a list of items that needs to be joined

User · Answer

Assuming join wasn t designed that way  which it is  as ATOzTOA pointed out   and it only took two parameters  you could still use the built-in reduce   gt  gt  gt  reduce os path join   quot c   quot   quot home quot   quot foo quot   quot bar quot   quot some txt quot     c  home  foo  bar  some txt   Same output like   gt  gt  gt  os path join    quot c   quot   quot home quot   quot foo quot   quot bar quot   quot some txt quot     c  home  foo  bar  some txt    Just for completeness and educational reasons  and for other situations where   doesn t work   Hint for Python 3 reduce was moved to the functools module

User · Answer

I stumbled over the situation where the list might be empty  In that case   os path join      the list with path components    Note the first argument  which will not alter the result

[python] Python os.path.join() on a list

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