I m getting Key error in python

Question

In my python program I am getting this error   KeyError   variablename    From this code   path   meta entry  path   strip         Can anyone please explain why this is happening

User · Answer

Let us make it simple if you re using Python 3 mydict     a   apple   b   boy   c   cat   check    c  in mydict if check      print  c key is present    If you need else condition mydict     a   apple   b   boy   c   cat   if  c  in mydict      print  key present   else      print  key not found    For the dynamic key value  you can also handle through try-exception block mydict     a   apple   b   boy   c   cat   try      print mydict  c    except KeyError      print  key value not found  mydict     a   apple   b   boy   c   cat

User · Answer

A KeyError generally means the key doesn t exist  So  are you sure the path key exists   From the official python docs   exception KeyError     Raised when a mapping  dictionary  key is not found in the set of   existing keys    For example    gt  gt  gt  mydict     a   1   b   2    gt  gt  gt  mydict  a    1   gt  gt  gt  mydict  c   Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  KeyError   c   gt  gt  gt    So  try to print the content of meta entry and check whether path exists or not    gt  gt  gt  mydict     a   1   b   2    gt  gt  gt  print mydict   a    1    b    2     Or  you can do    gt  gt  gt   a  in mydict True  gt  gt  gt   c  in mydict False

User · Answer

I received this error when I was parsing dict with nested for   cats     Tom     color    white    weight   8    Klakier     color    black    weight   10   cat attr      for cat in cats      for attr in cat          print cats cat  attr     Traceback   Traceback  most recent call last         File   lt input gt    line 3  in  lt module gt      KeyError   K    Because in second loop should be cats cat  instead just cat  what is just a key   So   cats     Tom     color    white    weight   8    Klakier     color    black    weight   10   cat attr      for cat in cats      for attr in cats cat           print cats cat  attr     Gives  black 10 white 8

User · Answer

For dict  just use if key in dict and don t use searching in key list if key in dict keys   The latter will be more time-consuming

User · Answer

For example  if this is a number    ouloulou       1 US      2 BR      3 FR       ouloulou 1      It s work perfectly  but  if you use for example    ouloulou input  select 1 2 or 3       it s doesn t work  because your input return string  1   So you need to use int    ouloulou int input  select 1 2 or 3

User · Answer

Yes  it is most likely caused by non-exsistent key   In my program  I used setdefault to mute this error  for efficiency concern   depending on how efficient is this line    gt  gt  gt  a  in mydict keys       I am new to Python too  In fact I have just learned it today  So forgive me on the ignorance of efficiency   In Python 3  you can also use this function   get key   default    function doc  1    It is said that it will never raise a key error

User · Answer

This means your array is missing the key you re looking for  I handle this with a function which either returns the value if it exists or it returns a default value instead   def keyCheck key  arr  default       if key in arr keys            return arr key      else          return default   myarray     key1  1   key2  2   print keyCheck  key1   myarray    default   print keyCheck  key2   myarray    default   print keyCheck  key3   myarray    default     Output   1 2  default

User · Answer

I fully agree with the Key error comments   You could also use the dictionary s get   method as well to avoid the exceptions   This could also be used to give a default path rather than None as shown below    gt  gt  gt  d     a  1   b  2   gt  gt  gt  x   d get  A  None   gt  gt  gt  print x None

[python] I'm getting Key error in python

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