How to extract numbers from a string in Python

Question

I would extract all the numbers contained in a string  Which is the better suited for the purpose  regular expressions or the isdigit   method   Example   line    hello 12 hi 89    Result    12  89

User · Answer

I m assuming you want floats not just integers so I d do something like this   l      for t in s split        try          l append float t       except ValueError          pass   Note that some of the other solutions posted here don t work with negative numbers    gt  gt  gt  re findall r  b d  b    he33llo 42 I  m a 32 string -30     42    32    30     gt  gt  gt   -3  isdigit   False

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This is more than a bit late  but you can extend the regex expression to account for scientific notation too   import re    Format is    lt string gt    lt expected output gt         ss      apple-12 34 ba33na fanc-14 23e-2yapple 45e5 67 56E 3            -12 34    33    -14 23e-2     45e5     67 56E 3             hello X42 I  m a Y-32 35 string Z30            42    -32 35    30             he33llo 42 I  m a 32 string -30             33    42    32    -30             h3110 23 cat 444 4 rabbit 11 2 dog             3110    23    444 4    11    2             hello 12 hi 89             12    89             4             4             I like 74 600 commas not 500             74 600    500             I like bad math 1 2  001             1     2     001      for s  r in ss      rr   re findall   -         d       d d d        d     eE  -    d      s      if rr    r          print  GOOD       else          print  WRONG   rr   should be   r    Gives all good   Additionally  you can look at the AWS Glue built-in regex

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I was looking for a solution to remove strings  masks  specifically from Brazilian phones numbers  this post not answered but inspired me  This is my solution    gt  gt  gt  phone number     55 11 8715-9877   gt  gt  gt     join  n for n in phone number if n isdigit      551187159877

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line2    hello 12 hi 89  temp1   re findall r  d    line2    through regular expression res2   list map int  temp1   print res2    Hi     you can search all the integers in the string through digit by using findall expression    In the second step create a list res2 and add the digits found in string to this list   hope this helps   Regards  Diwakar Sharma

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extract numbers from garbage string  s    12  n      3 14kjlw0xdadfackvj1 6e-19 amp  ghn334  newstr      join  ch if ch in  0123456789 -e  else      for ch in s  listOfNumbers    float i  for i in newstr split    print listOfNumbers   12 0  3 14  0 0  1 6e-19  334 0

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I d use a regexp     gt  gt  gt  import re  gt  gt  gt  re findall r  d     hello 42 I  m a 32 string 30     42    32    30     This would also match 42 from bla42bla  If you only want numbers delimited by word boundaries  space  period  comma   you can use  b     gt  gt  gt  re findall r  b d  b    he33llo 42 I  m a 32 string 30     42    32    30     To end up with a list of numbers instead of a list of strings    gt  gt  gt   int s  for s in re findall r  b d  b    he33llo 42 I  m a 32 string 30     42  32  30

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For phone numbers you can simply exclude all non-digit characters with  D in regex   import re  phone number     619  459-3635  phone number   re sub r  D       phone number  print phone number

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This answer also contains the case when the number is float in the string  def get first nbr from str input str                param input str  strings that contains digit and words      return  the number extracted from the input str     demo       ab324 23 123xyz   324 23       5abc44   0 5             if not input str and not isinstance input str  str           return 0     out number          for ele in input str          if  ele        and     not in out number  or ele isdigit                out number    ele         elif out number              break     return float out number

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The best option I found is below  It will extract a number and can eliminate any type of char   def extract nbr input str       if input str is None or input str                return 0      out number          for ele in input str          if ele isdigit                out number    ele     return float out number

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To catch different patterns it is helpful to query with different patterns  Setup all the patterns that catch different number patterns of interest   finds commas  12 300 or 12 300 00    d      d     finds floats  0 123 or  123    d       d     finds integers  123    d    Combine with pipe       into one pattern with multiple or conditionals   Note  Put complex patterns first else simple patterns will return chunks of the complex catch instead of the complex catch returning the full catch   p      d      d     d       d     d     Below  we ll confirm a pattern is present with re search    then return an iterable list of catches  Finally  we ll print each catch using bracket notation to subselect the match object return value from the match object  s    he33llo 42 I  m a 32 string 30 444 4 12 001   if re search p  s  is not None      for catch in re finditer p  s           print catch 0     catch is a match object  Returns  33 42 32 30 444 4 12 001

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Since none of these dealt with real world financial numbers in excel and word docs that I needed to find  here is my variation  It handles ints  floats  negative numbers  currency numbers  because it doesn t reply on split   and has the option to drop the decimal part and just return ints  or return everything    It also handles Indian Laks number system where commas appear irregularly  not every 3 numbers apart   It does not handle scientific notation or negative numbers put inside parentheses in budgets -- will appear positive    It also does not extract dates  There are better ways for finding dates in strings   import re def find numbers string  ints True                   numexp   re compile r  -   d  d          d 2       optional - in front     numbers   numexp findall string          numbers    x replace         for x in numbers      if ints is True          return  int x replace         split      0   for x in numbers                  else          return numbers

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If you only want to extract only positive integers  try the following   gt  gt  gt  str    quot h3110 23 cat 444 4 rabbit 11 2 dog quot   gt  gt  gt   int s  for s in str split   if s isdigit     23  11  2   I would argue that this is better than the regex example because you don t need another module and it s more readable because you don t need to parse  and learn  the regex mini-language  This will not recognize floats  negative integers  or integers in hexadecimal format   If you can t accept these limitations  jmnas s answer below will do the trick

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Using Regex below is the way lines    quot hello 12 hi 89 quot  import re output       repl str   re compile   d    d    repl str   re compile    d      t   r  d    d   line   lines split   for word in line          match   re search repl str  word          if match              output append float match group     print  output   with findall re findall r  d     quot hello 12 hi 89 quot     12    89    re findall r  b d  b    quot hello 12 hi 89 33F AC 777 quot     12    89    777

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I am amazed to see that no one has yet mentioned the usage of itertools groupby as an alternative to achieve this   You may use itertools groupby   along with str isdigit   in order to extract numbers from string as   from itertools import groupby my str    hello 12 hi 89   l    int    join i   for is digit  i in groupby my str  str isdigit  if is digit    The value hold by l will be    12  89    PS  This is just for illustration purpose to show that as an alternative we could also use groupby to achieve this  But this is not a recommended solution  If you want to achieve this  you should be using accepted answer of fmark based on using list comprehension with str isdigit as filter

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I am just adding this answer because no one added one using Exception handling and because this also works for floats  a      line    abcd 1234 efgh 56 78 ij  for word in line split        try          a append float word       except ValueError          pass print a    Output     1234 0  56 78

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jmnas  I liked your answer  but it didn t find floats   I m working on a script to parse code going to a CNC mill and needed to find both X and Y dimensions that can be integers or floats  so I adapted your code to the following   This finds int  float with positive and negative vals   Still doesn t find hex formatted values but you could add  x  and  A  through  F  to the num char tuple and I think it would parse things like  0x23AC    s    hello X42 I  m a Y-32 35 string Z30  xy     X    Y   num char               -    l       tokens   s split   for token in tokens       if token startswith xy           num              for char in token                print char              if char isdigit   or  char in num char                   num   num   char          try              l append float num           except ValueError              pass  print l

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If you know it will be only one number in the string  i e  hello 12 hi   you can try filter  For example  In  1   int    join filter str isdigit   200 grams     Out 1   200 In  2   int    join filter str isdigit   Counters  55     Out 2   55 In  3   int    join filter str isdigit   more than 23 times     Out 3   23  But be carefull       In  4   int    join filter str isdigit   200 grams 5     Out 4   2005

[python] How to extract numbers from a string in Python?

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