Check if a string contains a number

Question

Most of the questions I ve found are biased on the fact they re looking for letters in their numbers  whereas I m looking for numbers in what I d like to be a numberless string  I need to enter a string and check to see if it contains any numbers and if it does reject it   The function isdigit   only returns True if ALL of the characters are numbers  I just want to see if the user has entered a number so a sentence like  I own 1 dog  or something   Any ideas

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You can use range with count to check how many times a number appears in the string by checking it against the range   def count digit a       sum   0     for i in range 10           sum    a count str i       return sum  ans   count digit  apple3rh5   print ans    This print 2

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import string import random n   10  p       while  string ascii uppercase not in p  and  string ascii lowercase not in p  and  string digits not in p       for   in range n           state   random randint 0  2          if state    0              p   p   chr random randint 97  122           elif state    1              p   p   chr random randint 65  90           else              p   p   str random randint 0  9       break print p    This code generates a sequence with size n which at least contain an uppercase  lowercase  and a digit  By using the while loop  we have guaranteed this event

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I m surprised that no-one mentionned this combination of any and map   def contains digit s       isdigit   str isdigit     return any map isdigit s     in python 3 it s probably the fastest there  except maybe for regexes  is because it doesn t contain any loop  and aliasing the function avoids looking it up in str     Don t use that in python 2 as map returns a list  which breaks any short-circuiting

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What about this one   import string  def containsNumber line       res   False     try          for val in line split                if  float val strip string punctuation                     res   True                 break     except ValueError          pass     return res  containsNumber  234 12 a22     returns True containsNumber  234 12L a22     returns False containsNumber  234 12  a22     returns True

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alp num    x for x in string split   if x isalnum   and re search r  d  x  and  re search r  a-z   x    print alp num    This returns all the string that has both alphabets and numbers in it  isalpha   returns the string with all digits or all characters

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use str isalpha     Ref  https   docs python org 2 library stdtypes html str isalpha     Return true if all characters in the string are alphabetic and there   is at least one character  false otherwise

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This too will work  if any i isdigit   for i in s       print  quot True quot

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You can use NLTK method for it   This will find both  1  and  One  in the text   import nltk   def existence of numeric data text       text nltk word tokenize text      pos   nltk pos tag text      count   0     for i in range len pos            word   pos tag   pos i          if pos tag     CD               return True     return False  existence of numeric data  We are going out  Just five you and me

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Also  you could use regex findall  It s a more general solution since it adds more control over the length of the number  It could be helpful in cases where you require a number with minimal length  True if len    join re findall   d     67389kjsdk      gt  0 else False  Hope it helps some else

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You can use any function  with the str isdigit function  like this   gt  gt  gt  def hasNumbers inputString           return any char isdigit   for char in inputString        gt  gt  gt  hasNumbers  I own 1 dog   True  gt  gt  gt  hasNumbers  I own no dog   False   Alternatively you can use a Regular Expression  like this   gt  gt  gt  import re  gt  gt  gt  def hasNumbers inputString           return bool re search r  d   inputString         gt  gt  gt  hasNumbers  I own 1 dog   True  gt  gt  gt  hasNumbers  I own no dog   False

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You can accomplish this as follows   if a string isdigit         do this    else       do that    https   docs python org 2 library stdtypes html str isdigit  Using  isdigit   also means not having to resort to exception handling  try except  in cases where you need to use list comprehension  try except is not possible inside a list comprehension

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I ll make the  zyxue answer a bit more explicit   RE D   re compile   d    def has digits string       res   RE D search string      return res is not None  has digits  asdf1   Out  True  has digits  asdf   Out  False   which is the solution with the fastest benchmark from the solutions that  zyxue proposed on the answer

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Simpler way to solve is as  s    1dfss3sw235fsf7s  count   0 temp   list s  for item in temp      if item isdigit             count   count   1     else          pass print count

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You could apply the function isdigit   on every character in the String  Or you could use regular expressions   Also I found How do I find one number in a string in Python  with very suitable ways to return numbers  The solution below is from the answer in that question   number   re search r  d    yourString  group     Alternatively   number   filter str isdigit  yourString    For further Information take a look at the regex docu  http   docs python org 2 library re html  Edit  This Returns the actual numbers  not a boolean value  so the answers above are more correct for your case  The first method will return the first digit and subsequent consecutive digits  Thus 1 56 will be returned as 1   10 000 will be returned as 10  0207-100-1000 will be returned as 0207    The second method does not work   To extract all digits  dots and commas  and not lose non-consecutive digits  use   re sub     d           yourString

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This probably isn t the best approach in Python  but as a Haskeller this lambda map approach made perfect sense to me and is very short   anydigit   lambda x  any map str isdigit  x    Doesn t need to be named of course  Named it could be used like anydigit  abc123    which feels like what I was looking for

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You can use a combination of any and str isdigit   def num there s       return any i isdigit   for i in s    The function will return True if a digit exists in the string  otherwise False   Demo    gt  gt  gt  king    I shall have 3 cakes   gt  gt  gt  num there king  True  gt  gt  gt  servant    I do not have any cakes   gt  gt  gt  num there servant  False

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https   docs python org 2 library re html  You should better use regular expression  It s much faster   import re  def f1 string       return any i isdigit   for i in string    def f2 string       return re search   d   string      if you compile the regex string first  it s even faster RE D   re compile   d   def f3 string       return RE D search string     Output from iPython   In  18    timeit  f1  assdfgag123     1000000 loops  best of 3  1 18   s per loop    In  19    timeit  f2  assdfgag123     1000000 loops  best of 3  923 ns per loop    In  20    timeit  f3  assdfgag123     1000000 loops  best of 3  384 ns per loop

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any and ord can be combined to serve the purpose as shown below    gt  gt  gt  def hasDigits s           return any  48  lt   ord char   lt   57 for char in s       gt  gt  gt  hasDigits  as1   True  gt  gt  gt  hasDigits  as   False  gt  gt  gt  hasDigits  as9   True  gt  gt  gt  hasDigits  as    False  gt  gt  gt  hasDigits  1as   True  gt  gt  gt    A couple of points about this implementation    any is better because it works like short circuit expression in C Language and will return result as soon as it can be determined i e  in case of string  a1bbbbbbc   b s and  c s won t even be compared  ord is better because it provides more flexibility like check numbers only between  0  and  5  or any other range  For example if you were to write a validator for Hexadecimal representation of numbers you would want string to have alphabets in the range  A  to  F  only

[python] Check if a string contains a number

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