How does tuple comparison work in Python

Question

I have been reading the Core Python programming book  and the author shows an example like     4  5   lt   3  5    Equals false   So  I m wondering  how why does it equal false  How does python compare these two tuples   Btw  it s not explained in the book

User · Answer

I had some confusion before regarding integer comparsion, so I will explain it to be more beginner friendly with an example

a = ('A','B','C') # see it as the string "ABC" b = ('A','B','D')

A is converted to its corresponding ASCII ord('A') #65 same for other elements

So, >> a>b # True you can think of it as comparing between string (It is exactly, actually)

the same thing goes for integers too.

x = (1,2,2) # see it the string "123" y = (1,2,3) x > y # False

because (1 is not greater than 1, move to the next, 2 is not greater than 2, move to the next 2 is less than three -lexicographically -)

The key point is mentioned in the answer above

think of it as an element is before another alphabetically not element is greater than an element and in this case consider all the tuple elements as one string.

User · Answer

The Python documentation does explain it      Tuples and lists are compared   lexicographically using comparison of   corresponding elements  This means   that to compare equal  each element   must compare equal and the two   sequences must be of the same type and   have the same length

User · Answer

Tuples are compared position by position  the first item of the first tuple is compared to the first item of the second tuple  if they are not equal  i e  the first is greater or smaller than the second  then that s the result of the comparison  else the second item is considered  then the third and so on  See Common Sequence Operations   Sequences of the same type also support comparisons  In particular  tuples and lists are compared lexicographically by comparing corresponding elements  This means that to compare equal  every element must compare equal and the two sequences must be of the same type and have the same length   Also Value Comparisons for further details   Lexicographical comparison between built-in collections works as follows   For two collections to compare equal  they must be of the same type  have the same length  and each pair of corresponding elements must compare equal  for example   1 2      1 2  is false because the type is not the same   Collections that support order comparison are ordered the same as their first unequal elements  for example   1 2 x   lt    1 2 y  has the same value as x  lt   y   If a corresponding element does not exist  the shorter collection is ordered first  for example   1 2   lt   1 2 3  is true     If not equal  the sequences are ordered the same as their first differing elements  For example  cmp  1 2 x    1 2 y   returns the same as cmp x y   If the corresponding element does not exist  the shorter sequence is considered smaller  for example   1 2   lt   1 2 3  returns True   Note 1   lt  and  gt  do not mean  quot smaller than quot  and  quot greater than quot  but  quot is before quot  and  quot is after quot   so  0  1   quot is before quot   1  0   Note 2  tuples must not be considered as vectors in a n-dimensional space  compared according to their length  Note 3  referring to question https   stackoverflow com questions 36911617 python-2-tuple-comparison  do not think that a tuple is  quot greater quot  than another only if any element of the first is greater than the corresponding one in the second

User · Answer

The python 2 5 documentation explains it well      Tuples and lists are compared lexicographically using comparison of corresponding elements  This means that to compare equal  each element must compare equal and the two sequences must be of the same type and have the same length       If not equal  the sequences are ordered the same as their first differing elements  For example  cmp  1 2 x    1 2 y   returns the same as cmp x y   If the corresponding element does not exist  the shorter sequence is ordered first  for example   1 2   lt   1 2 3       Unfortunately that page seems to have disappeared in the documentation for more recent versions

[python] How does tuple comparison work in Python?

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