Matlab Split-String - string

Question

Hello,
I have a little problem.
I have a txt file with over 200mb.
It looks like:
%Hello World
%second sentences
%third;
%example
12.02.2014
;-400;-200;200
;123;233;434
%Hello World
%second sentences
%third
%example
12.02.2014
;-410;200;20300
;63;23;43
;23;44;78213
..
... ...
I need only the Values after the semicolon like:
Value1{1,1}=[-400]; Value{1,2}=[-200]; and Value{1,3}=[200]
Value2{1,1}=[123]; Value{1,2}=[233]; and Value{1,3}=[434]
and so on.
Hase someone an ideas, how i can split the values in a cell array or vektor?
Thus, the variables must be:
Var1=[-400 -200 200;
434 233 434;
Var2=[
-410 200 20300;
63 23 43;
23 44 28213]
I will seperate, after every date in a another Value. Example when i have 55 Dates, i will have 55 Values.
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Answer 1

This could be one approach assuming a uniformly structured data (3 valid numbers per row) -
%// Read in entire text data into a cell array
data = importdata('sample.txt','');
%// Remove empty lines
data = data(~cellfun('isempty',data))
%// Find boundaries based on delimiter "%example"
exmp_delim_matches = arrayfun(#(n) strcmp(data{n},'%example'),1:numel(data))
bound_idx = [find(exmp_delim_matches) numel(exmp_delim_matches)]
%// Find lines that start with delimiter ";"
matches_idx = find(arrayfun(#(n) strcmp(data{n}(1),';'),1:numel(data)))
%// Select lines that start with character ";" and split lines based on it
%// Split selected lines based on the delimiter ";"
split_data = regexp(data(matches_idx),';','split')
%// Collect all cells data into a 1D cell array
all_data = [split_data{:}]
%// Select only non-empty cells and convert them to a numeric array.
%// Finally reshape into a format with 3 numbers per row as final output
out = reshape(str2double(all_data(~cellfun('isempty',all_data))),3,[]).' %//'
%// Separate out lines based on the earlier set bounds
out_sep = arrayfun(#(n) out(matches_idx>bound_idx(n) & ...
matches_idx<bound_idx(n+1),:),1:numel(bound_idx)-1,'Uni',0)
%// Display results for verification
celldisp(out_sep)
Code run -
out_sep{1} =
-400 -200 200
123 233 434
out_sep{2} =
-410 200 20300
63 23 43
23 44 78213

Answer 2

A brute force approach would be to open up your file, then read each line one at a time. With each line, you check to see if the first character is a semi-colon and if it is, split up the string by the ; delimiter from the second character of the line up until the end. You will receive a cell array of strings, so you'd have to convert this into an array of numbers. Because you will probably have each line containing a different amount of numbers, let's store each array into a cell array where each element in this cell array will contain the numbers per line. As such, do something like this. Let's assume your text file is stored in text.txt:
fid = fopen('text.txt');
if fid == -1
error('Cannot find file');
end
nums = {};
while true
st = fgetl(fid);
if st == -1
break;
end
if st(1) == ';'
st_split = strsplit(st(2:end), ';');
arr = cellfun(#str2num, st_split);
nums = [nums arr];
end
end
Let's go through the above code slowly. We first use fopen to open up the file for reading. We check to see if the ID returned from fopen is -1 and if that's the case, we couldn't find or open the file so spit out an error. Next, we declare an empty cell array called nums which will store our numbers that you are getting when parsing your text file.
Now, until we reach the end of the file, get one line of text starting from the top of the file and we proceed to the end. We use fgetl for this. If we read a -1, this means we have reached the end of the file, so get out of the loop. Else, we check to see if the first character is ;. If it is, then we take a look at the second character until the end of this line, and split the string based on the ; character with strsplit. The result of this will be a cell array of strings where each element is the string representation of your number. You need to convert this cell array back into a numeric array, and so what you would need to do is apply str2num to each element in this cell. You can either use a loop to go through each cell, or you can conveniently use [cellfun](http://www.mathworks.com/help/matlab/ref/cellfun.html to allow you to go through each element in this cell and convert the string representation into a numeric value. The resulting output of cellfun will give you a numeric array representation of each value delimited by the ; character for that line. We then place this array into a single cell stored in nums.
The end result of this entire code will give you numeric arrays that are based on what you are looking for stored in nums.
Warning
I am assuming that your text file only has numbers delimited by ; characters if we encounter a line that starts with ;. If this is not the case, then my code will not work. I'm assuming this isn't the case!