Convert alphabet letters to number in Python

Question

How can the following be finished   characters     a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  t  u  v  w  x  y  z   numbers     1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24   text   raw input   Write text       I ve tried to solve it many ways  but couldn t get to the pint  I want to make exc  If I type  hello  the output to be in numbers lined like in alphabet  Example a   1  lt  in alphabet

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gt  gt  gt   str ord string lower c   - ord  a     1  for c in string letters    1    2    3    4    5    6    7    8    9    10    11    12    13    14    15    16    17    18    19    20    21    22    23    24    25    26    1    2    3    4    5    6    7    8    9    10    11    12    13    14    15    16    17    18    19    20    21    22    23    24     25    26

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Here is my solution for a problem where you want to convert all the letters in a string with position of those letters in English alphabet and return a string of those nos   https   gist github com bondnotanymore e0f1dcaacfb782348e74fac8b224769e  Let me know if you want to understand it in detail I have used the following concepts   - List comprehension  - Dictionary comprehension

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def letter to int letter       alphabet   list  abcdefghijklmnopqrstuvwxyz       return alphabet index letter    1   here  the index  x  function returns the position value of x if the list contains x

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import string   Amin my name   str input  quot Enter a your name   quot    numbers           characters        output            for x  y in zip range 1  27   string ascii lowercase       numbers append x      characters append y   print numbers  print characters  print  quot ---------------------------------------------------------------------- quot    input   my name input   input lower    for character in input      number   ord character  - 96     output append number  print output  print  quot ---------------------------------------------------------------------- quot    sum   0 lent out   len output  for i in range 0 lent out       sum   sum   output i   print  quot resulat sum is    quot   print  quot ----------------- quot    print sum       resualt is    1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26    a    b    c    d    e    f    g    h    i    j    k    l    m    n    o    p    q    r    s    t    u    v    w    x    y    z   ----------------------------------------------------------------------  1  13  9  14  ---------------------------------------------------------------------- resulat sum is    ----------------- 37

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If you are going to use this conversion a lot  consider calculating once and putting the results in a dictionary    gt  gt  gt  import string  gt  gt  gt  di dict zip string letters  ord c  32 for c in string letters     gt  gt  gt  di  c    3   The advantage is dictionary lookups are very fast vs iterating over a list on every call    gt  gt  gt  for c in sorted di keys      gt  gt  gt     print   0   1     format c  di c     what you would expect

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If you are looking the opposite like 1   A   2   B etc  you can use the following code  Please note that I have gone only up to 2 levels as I had to convert divisions in a class to A  B  C etc       loopvariable   0      numberofdivisions   53     while  loopvariable  lt numberofdivisions           if loopvariable lt 26               print chr 65 loopvariable           loopvariable   1         if loopvariable  gt  26 and loopvariable  lt 53               print chr 65  chr 65  loopvariable-27

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If you are just looking to map a number to a letter  then just do something simple like this   def letter to index letter        alphabet    abcdefghijklmnopqrstuvwxyz      return next  i for i   letter in enumerate  alphabet  if  letter    letter   None    Of course if you want to have it start at 1  then just add  i 1 for i      etc

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Here s something I use to convert excel column letters to numbers  so a limit of 3 letters but it s pretty easy to extend this out if you need more   Probably not the best way but it works for what I need it for   def letter to number letters       letters   letters lower       dictionary     a  1  b  2  c  3  d  4  e  5  f  6  g  7  h  8  i  9  j  10  k  11  l  12  m  13  n  14  o  15  p  16  q  17  r  18  s  19  t  20  u  21  v  22  w  23  x  24  y  25  z  26      strlen   len letters      if strlen    1          number   dictionary letters      elif strlen    2          first letter   letters 0          first number   dictionary first letter          second letter   letters 1          second number   dictionary second letter          number    first number   26    second number     elif strlen    3          first letter   letters 0          first number   dictionary first letter          second letter   letters 1          second number   dictionary second letter          third letter   letters 2          third number   dictionary third letter          number    first number   26   26     second number   26    third number     return number

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This is a function I used to use for this purpose  Works for both uppercase and lowercase   def convert char old       if len old     1          return 0     new   ord old      if 65  lt   new  lt   90            Upper case letter         return new - 64     elif 97  lt   new  lt   122            Lower case letter         return new - 96       Unrecognized character     return 0

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What about something like this   print  ord char  - 96 for char in raw input  Write Text     lower      ord list comprehension ASCII character codes  EDIT Since you asked me to explain I will    though it has been explained pretty well in the comments already by       Let s do this in more that one line to start   input   raw input  Write Text     input   input lower   output      for character in input      number   ord character  - 96     output append number  print output   This does the same thing  but is more readable   Make sure you can understand what is going on here before you try to understand my first answer   Everything here is pretty standard  simple Python   The one thing to note is the ord function   ord stand for ordinal  and pretty much every high level language will have this type of function available   It gives you a mapping to the numerical representation of any character   The inverse function of ord is called chr     chr ord  x        x    for any character  not just x    If you test for yourself  the ordinal of a is 97  the third link I posted above will show the complete ASCII character set    Each lower case letter is in the range 97-122  26 characters    So  if you just subtract 96 from the ordinal of any lower case letter  you will get its position in the alphabet assuming you take  a     1   So  ordinal of  b     98   c     99  etc   When you subtract 96   b     2   c     3  etc     The rest of the initial solution I posted is just some Python trickery you can learn called list comprehension   But  I wouldn t focus on that as much as I would focus on learning to solve the problem in any language  where ord is your friend   I hope this helps

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You can use chr   and ord   to convert betweeen letters and int numbers   Here is a simple example    gt  gt  gt  chr 97   a   gt  gt  gt  ord  a   97

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If the goal is to transform only the letters abcd    xyz and ABCD    XYZ   I would use a function   from string import letters def rank x  d   dict  letr n 26 1  for n letr in enumerate letters 0 52          return d x    I   ve written  0 52  because my Python 2 7 version displays the value   ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz                                                                                                                                               for the string letters argument   Because the parameter d receives a value as a default argument  the calculus of this value is performed only once  at the moment when the definition of the function is executed to produce the function object  So  the function can then be used without this value to be calculated again  even if the function is appealed three thousand times   By the way  lower   isn   t used again for each appeal of the function  The case of upper letters has been treated during the construction of the default argument      One example of use   word    supercalifragilisticexpialidocious  print    join  letter if rank letter  3  0 else     for letter in word    result   s pe  a    ag   st  e p a  d     s     It can be used with map   too    print map rank  ImmunoElectroPhoresis     result    9  13  13  21  14  15  5  12  5  3  20  18  15  16  8  15  18  5  19  9  19

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Something like this   str ord c  amp 31  for c in text

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Not to be too basic  but this    gt  gt  gt  char1     a  b  c  d  e  f  g  h  i  j  k  l                m  n  o  p  q  r  s  t  u  v  w  x  y  z     is very different than this    gt  gt  gt  char2     a   b   c   d   e   f   g   h   i   j   k   l                   m   n   o   p   q   r   s   t   u   v   w   x   y   z     The first  without commas and what you have in your question  is a one element list with a 26 element string  The second is a 26 element list each a single character in length   If you print each     gt  gt  gt  print char1  len char1   len char1 0     abcdefghijklmnopqrstuvwxyz   1 26  gt  gt  gt  print char2  len char2   len char2 0     a    b    c    d    e    f    g    h    i    j    k    l     m    n    o    p    q   r    s    t    u    v    w    x    y    z   26 1   It becomes apparent that it takes an additional step to turn the individual characters of char1 into an iterable    If you have the sequence of characters  a  through  z  and or  A  through  Z   you can easily return the number of the character with list comprehension    gt  gt  gt   ord x  32 for x in char2   1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16   17  18  19  20  21  22  23  24  25  26    For the type of data structure you have  you need to access the string first    gt  gt  gt   ord x  32 for x in char1 0    1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16   17  18  19  20  21  22  23  24  25  26    So if your code listing is the same as in your question  that may be your issue    A reasonable alternative is   ord x lower   -96 for x in char1 0    You can see that your characters   a  b  c       without the commas  is just the same as typing all the characters in a string in a list like this   abc         So now try     gt  gt  gt  import string   gt  gt  gt   ord x lower   -96 for x in string letters    1 2    26  1 2 3   26         my ellipses    gt  gt  gt  char3  string letters      one string as element 0    gt  gt  gt   ord x  32 for x in char3 0     gt  gt  gt   ord x  32 for x in  string letters  0

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You can map the alphabet to a list and return the index of each one as per the below    import string  alphabet string ascii lowercase  alphabet  abcdefghijklmnopqrstuvwxyz    Get the character index   ex  e   print chars find  e     This will return 4

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This is very simple script to do what you are asking for   try this     usr bin env python3  def remove string        return string replace  quot   quot    quot  quot    dict     a    1         b    2        c    3        d    4        e    5        f    6        g    7        h    8        i    9        j    10        k    11        l    12        m    13        n    14        o    15        p    16        q    17        r    18        s    19        t    20        u    21        v    22        w    23        x    24        y    25        z    26      word   remove input       for x in word      print dict x       or     index   0  for x in word      print dict word index        index   index   1

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Use this function  It converts a string of alphabet to its equivalent digit value   def convAlph2Num sent       alphArray   list string ascii lowercase      alphSet   set alphArray      sentArray   list sent lower        x          for u in sentArray          if u in alphSet              u   alphArray index u    1             x append u      print x      return

[python] Convert alphabet letters to number in Python

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