How to check if a value exists in a dictionary python

Question

I have the following dictionary in python    d     1    one    3    three    2    two    5    five    4    four     I need a way to find if a value such as  one  or  two  exists in this dictionary   For example  if I wanted to know if the index  1  existed I would simply have to type     1  in d   And then python would tell me if that is true or false  however I need to do that same exact thing except to find if a value exists

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Use dictionary views   if x in d viewvalues        dosomething

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In Python 3  you can use  quot one quot  in d values    to test if  quot one quot  is among the values of your dictionary  In Python 2  it s more efficient to use  quot one quot  in d itervalues    instead  Note that this triggers a linear scan through the values of the dictionary  short-circuiting as soon as it is found  so this is a lot less efficient than checking whether a key is present

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Different types to check the values exists  d     key1   value1    key2   value2    value10  in d values     gt  gt  False   What if list of values  test     key1     value4    value5    value6     key2     value9     key3     value6     value4  in  x for v in test values   for x in v   gt  gt True   What if list of values with string values  test     key1     value4    value5    value6     key2     value9     key3     value6     key5   value10   values   test values    value10  in  x for v in test values   for x in v  or  value10  in values  gt  gt True

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gt  gt  gt  d     1    one    3    three    2    two    5    five    4    four    gt  gt  gt   one  in d values   True   Out of curiosity  some comparative timing    gt  gt  gt  T lambda    one  in d itervalues    repeat    0 28107285499572754  0 29107213020324707  0 27941107749938965   gt  gt  gt  T lambda    one  in d values    repeat    0 38303399085998535  0 37257885932922363  0 37096405029296875   gt  gt  gt  T lambda    one  in d viewvalues    repeat    0 32004380226135254  0 31716084480285645  0 3171098232269287    EDIT  And in case you wonder why    the reason is that each of the above returns a different type of object  which may or may not be well suited for lookup operations    gt  gt  gt  type d viewvalues     lt type  dict values  gt   gt  gt  gt  type d values     lt type  list  gt   gt  gt  gt  type d itervalues     lt type  dictionary-valueiterator  gt    EDIT2  As per request in comments      gt  gt  gt  T lambda    four  in d itervalues    repeat    0 41178202629089355  0 3959040641784668  0 3970959186553955   gt  gt  gt  T lambda    four  in d values    repeat    0 4631338119506836  0 43541407585144043  0 4359898567199707   gt  gt  gt  T lambda    four  in d viewvalues    repeat    0 43414998054504395  0 4213531017303467  0 41684913635253906

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Python dictionary has get key  function  gt  gt  gt  d get key   For Example   gt  gt  gt  d     1    one    3    three    2    two    5    five    4    four    gt  gt  gt  d get  3    three   gt  gt  gt  d get  10   None  If your key does nt exist  will return None value   foo   d key    raise error if key doesn t exist foo   d get key    return None if key doesn t exist   Content relevant to versions less than 3 0 and greater than 5 0

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In Python 3 you can use the values   function of the dictionary  It returns a view object of the values  This  in turn  can be passed to the iter function which returns an iterator object  The iterator can be checked using in  like this    one  in iter d values      Or you can use the view object directly since it is similar to a list    one  in d values

[python] How to check if a value exists in a dictionary (python)

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