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How to discard all punctuation from a text file

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Fateme Jalali
Fateme Jalali el 18 de En. de 2016
Comentada: Image Analyst el 16 de Sept. de 2017
Hello, I need a MATLAB code to discard all punctuation and signs from a text file.I want to keep only characters and numbers.Thanks.

Respuesta aceptada

John BG
John BG el 19 de En. de 2016
Star Stride is right but perhaps Fateme wants to keep the spaces, because space is not punctuation spaces will help reading the resulting string. The initial string
str1 = 'Hello, I need 1 MATLAB code to discard all punctuation, and signs from 9 text files.'
Lstr1=length(str1)
the characters that have to remain are
str_space='\s'
str_caps='[A-Z]'
str_ch='[a-z]'
str_nums='[0-9]'
their respective positions within str1 are
ind_space=regexp(str1,str_space)
ind_caps=regexp(str1,str_caps)
ind_chrs=regexp(str1,str_ch)
ind_nums=regexp(str1,str_nums)
mask=[ind_space ind_caps ind_chrs ind_nums]
now let's find the position of all punctuation characters
num_str2=1:1:Lstr1
num_str2(mask)=[]
now num_str2 contains the positions of punctuation characters to remove
str3=str1
str3(num_str2)=[]
str3 contains the resulting string without any other character than alphabetical characters and numbers.
str3 =
Hello I need 1 MATLAB code to discard all punctuation and signs from 9 text files
Hope it helps in your reading.
John
  1 comentario
Fateme Jalali
Fateme Jalali el 19 de En. de 2016
thank you.After discarding all punctuation i want to put a white space before the first character and after the last one.How can i do it?thanks

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Más respuestas (3)

Star Strider
Star Strider el 18 de En. de 2016
Editada: Star Strider el 19 de En. de 2016
One possible approach:
str = 'Hello, I need 1 MATLAB code to discard all punctuation, and signs from 9 text files.';
Idx = regexp(str, '[^. , !]');
Result = str(Idx)
EDIT — To keep the spaces, just remove them from the regexp pattern string (in this instance, I was telling it to exclude spaces as well as the punctuation):
str = 'Hello, I need 1 MATLAB code to discard all punctuation, and signs from 9 text files.';
Idx = regexp(str, '[^.,!]');
Result = str(Idx)
Result =
Hello I need 1 MATLAB code to discard all punctuation and signs from 9 text files
You can add as many other punctuation or other characters as necessary between the square brackets ‘[]’, depending on what appears in your strings that you do not want in the result.
  2 comentarios
Mubashir
Mubashir el 16 de Sept. de 2017
I want to use this in table. I can't remove punctuation's in whole column.
Image Analyst
Image Analyst el 16 de Sept. de 2017
So then go down the table's column one row at a time. What's wrong with that? It's easy.

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Walter Roberson
Walter Roberson el 19 de En. de 2016
https://www.mathworks.com/matlabcentral/newsreader/view_thread/127125
  2 comentarios
Fateme Jalali
Fateme Jalali el 19 de En. de 2016
thank you.After discarding all punctuation i want to put a white space before the first character and after the last one.How can i do it?thanks
Walter Roberson
Walter Roberson el 19 de En. de 2016
YourString = [' ' YourString ' '];

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Image Analyst
Image Analyst el 19 de En. de 2016
Yet another way:
str = 'Hello, ~!@#$^&*()_+.,<>;"?I need 1 MATLAB code to discard all punctuation, and signs from 9 text files.'
% Get logical index to keep space, numbers, and upper and lower case letters.
keeperIndexes = str == ' ' | (str>='0' & str<='9') | ...
(str>='a' & str<='z') | (str>='A' & str<='Z');
strOut = str(keeperIndexes) % Extract only those elements

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