How to count the number of each character from a text file (and the frequency of it)?

Create a function that takes a text file as input and returns a vector of size 26 with the frequency in percent of each character a, b, . . . z (not sensitive to case.) The frequency must be computed as the number of occurences divided by the total number of characters from a to z that occur, multiplied by one hundred. All other letters such as ø and ä as well as all symbols must be ignored.

Answer 1

[Azzi Abdelmalek]

s=importdata('file.txt')
str=upper(s(:))
str=[str{:}]
AZ='A':'Z'
long=sum(ismember(str,AZ));
for k=1:numel(AZ)
  freq(k,1)=100*sum(ismember(str,AZ(k)))/long
end

Answer 2

[Mounic Kumar]

function charnum = char_counter(fname,A)
fid = fopen(fname,'rt');
if fid < 0
    charnum = -1;
    return
end
if fid >0 && ischar(A)
    k=0;
    oneread = fgets(fid);
    while ischar(oneread)
        k = k + count(oneread,A);
        oneread = fgets(fid);
    end
    charnum = k;
else 
    charnum = -1;
end
fclose(fid);

Answer 3

[Amit Dubey]

function n=char_counter(fname,character)
fid=fopen(fname,'rt');
if fid<0 
    n=-1;
    return;
elseif ~ischar(character)
    n=-1;
    return;
end
end
c=0;
ol=fgets(fid);
while ischar(ol) 
    c=c+count(ol,character);
    ol=fgets(fid);
end
n=c;
fclose(fid);

[Walter Roberson]

If the file open works but ischar(character) fails, then you leave the file open when you return.

[Amit Dubey]

Thank you, just made required modifications

Answer 4

[Priyamvada Shankar]

Please Help me with this ..function called char_counter that counts the number of a certain character in a text file. The function takes two input arguments, fname, a char vector of the filename and character, the char it counts in the file. The function returns charnum, the number of characters found. If the file is not found or character is not a valid char, the function return -1. As an example, consider the following run. The file "simple.txt" contains a single line: "This file should have exactly three a-s..."

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Priyamvada Shankar]

What is it? If you know the answer please help me.

[Walter Roberson]

You did not ask a question, so there is no answer.

[Priyamvada Shankar]

Okay thank you so much

[Walter Roberson]

The link I posted describes how to ask the kinds of questions that people here are willing to assist with.

[TEJAS M]

%can any one pls help me what is the cause of error in this.
%ERROR -->Test with all visible characters
%Variable charnum has an incorrect value.
%When testing with ' ' your solution returned 1 which is incorrect. (75444)


function charnum = char_counter(fname,character) 

fid = fopen(fname,'rt');

if fid < 0 || ~ischar(character) || ~ischar(fname) || length(fname)==0 || length(character)==0 || isempty(fname) || isempty(character)
    charnum=-1;
else
        l=[];
        oneline = fgets(fid);
    while ischar(oneline)
         l=oneline;;
         oneline = fgets(fid);    
        end
z=count(l,character);
    if z>0
        charnum=z;
    elseif z<0
        charnum=-1;
    else
        charnum=-1;
    end
end
end

[Walter Roberson]

Why are you skipping down to the last line of the file?

[Walter Roberson]

note: your function returns -1 if the character is valid but not found. Your function should only be returning -1 if the file is not found or if the input is not a valid scalar character.