Reading text file and dealing with numbers - matlab

Question

I'm attempting to count the number of letters in a text file, but unfortunately I keep getting stuck if numbers are involved.
So far I have been able to deal with letters and symbols, but unfortunately the ischar function doesn't help me when it comes to numbers.
function ok = lets(file_name)
fid = fopen(file_name, 'rt');
if fid < 0
ok = -1;
end
C = [];
D = [];
oneline = fgets(fid);
while ischar(oneline)
C = oneline(isletter(oneline));
W = length(C);
D = [D ; W];
oneline = fgets(fid);
end
total = 0;
for i = 1:length(D)
total = D(i) + total;
end
ok = total;
How can I deal with counting letters if there are also numbers in a text file?

Answer 1

I approached the problem the following way:
function ok = lets(file_name)
file = memmapfile( file_name, 'writable', false );
lowercase = [65:90];
uppercase = [97:122];
data = file.Data;
ok = sum(histc(data,lowercase)+histc(data,uppercase));
end
I mapped the file to memory using the memmapfile function and compared the data with the character encodings from this ASCII table. Lower case letters are represented by [65:90] and upper case letters by [97:122]. By applying the histc function, I got the frequency in which each letter appeared in the file. The total number of letters is given by adding all the frequencies up.
Note that I called histc twice to avoid having a bin from 90 to 97, which would count the []^_` characters.
I applied the function to a sample file called sample.txt containing the following lines:
abc23D&f![
k154&¨&skj
djaljaljds
Here is my output:
>> lets('sample.txt')
Elapsed time is 0.017783 seconds.
ans =
19
Edit:
Outputting ok=-1 for problems reading file:
function ok = lets(fclose(fid);file_name)
try
file = memmapfile( file_name, 'writable', false );
catch
file=[];
ok=-1;
end
if ~isempty(file)
lowercase = [65:90];
uppercase = [97:122];
data = file.Data;
ok = sum(histc(data,lowercase)+histc(data,uppercase));
end
end
With fopen approach, since you get the ok=-1 "by default":
function ok = lets(file_name)
fid = fopen(file_name, 'rt');
if fid < 0
ok = -1;
else
celldata=textscan(fid,'%s');
fclose(fid);
lowercase = [65:90];
uppercase = [97:122];
data = uint8([celldata{1}{:});
ok = sum(histc(data,lowercase)+histc(data,uppercase));
end
end

Answer 2

I think you are making this a lot more complected than it needs to be, just use isletter like you had and then use length.
function ok = lets(file_name)
%Original code as you had it
fid = fopen(file_name, 'rt');
if fid < 0
ok = -1;
end
%Initialize length
ok = 0;
%Get first line
oneline = fgets(fid);
%While line isn't empty
while oneline ~= -1
%remove everythin that's not a letter
oneline(~isletter(oneline)) = [];
%Add number of letters to output
ok = ok + length(oneline);
%Get next line
oneline = fgets(fid);
end
end
I used the input file,
Ar,TF,760,2.5e-07,1273.14,4.785688323049946e+24,24.80738364864047,37272905351.7263,37933372595.0276
Ar,TF,760,5e-07,1273.14,4.785688323049946e+24,40.3092219226107,2791140681.70926,2978668073.513113
Ar,TF,760,7.5e-07,1273.14,4.785688323049946e+24,54.80989010679312,738684259.1671219,836079550.0157251
and got 18, this counts the e's in the numbers, do you want these to be counted?