Object Equality and Identity

x == y

  • Tests the values of x and y for equality
  • Sequences are equal if every element is equal.
  • Dictionaries are equal if they have the same set of keys and all objects with same key have the same value.

x is y

  • Tests if x and y are exactly the same object.

x is not y

  • Tests if x and y are different objects

Notes

  • x == y may be true while x is not y
  • Comparisons between non-compatible types may not generate an error, but the result is arbitrary (although always the same for the same two objects)
<<< O'Reilly OSCON 2000, Introduction to Python, Slide 62
July 17, 2000, beazley@cs.uchicago.edu
>>>