How to check if an element of a list is a list in Python

Question

If we have the following list   list     UMM    Uma     Ulaster   Ulter      If I need to find out if an element in the list is itself a list  what can I replace aValidList in the following code with   for e in list      if e    aValidList          return True   Is there a special import to use   Is there a best way of checking if a variable element is a list

User · Accepted Answer

Use isinstance   if isinstance e  list     If you want to check that an object is a list or a tuple  pass several classes to isinstance   if isinstance e   list  tuple

User · Answer

Work out what specific properties of a list you want the items to have  Do they need to be indexable  Sliceable  Do they need an  append   method  Look up the abstract base class which describes that particular type in the collections module  Use isinstance   isinstance x  collections MutableSequence       You might ask  why not just use type x     list   You shouldn t do that  because then you won t support things that look like lists  And part of the Python mentality is duck typing      I see a bird that walks like a duck and swims like a duck and quacks like a duck  I call that bird a duck   In other words  you shouldn t require that the objects are lists  just that they have the methods you will need  The collections module provides a bunch of abstract base classes  which are a bit like Java interfaces  Any type that is an instance of collections Sequence  for example  will support indexing

User · Answer

Expression you are looking for may be        return any  isinstance e  list  for e in my list     Testing    gt  gt  gt  my list    1 2   gt  gt  gt  any  isinstance e  list  for e in my list   False  gt  gt  gt  my list    1 2   3 4 5    gt  gt  gt  any  isinstance e  list  for e in my list   True  gt  gt  gt

User · Answer

you can simply write   for item i in zip your list  range len your list         if type item     list          print f  item  at index  i  is a list

User · Answer

Probably  more intuitive way would be like this  if type e  is list      print  Found a list element inside the list

[python] How to check if an element of a list is a list (in Python)?

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