Matlab - preprocess CSV file - matlab

Question

I have a CSV file in a format similar to the following one:
title1
index columnA1 columnA2 columnA3
1 2 3 6
2 23 23 1
3 2 3 45
4 2 2 101
title2
index columnB1 columnB2 columnB3
1 23 53 6
2 22 13 1
3 5 4 43
4 8 6 102
I want to build a function readCustomCSV which receives a CSV file in the bellow illustrated format and a row index i and returns an output file with (for let's say i = 3) the following content:
title1
index columnA1 columnA2 columnA3
3 2 3 45
title2
index columnB1 columnB2 columnB3
3 5 4 43
Do you know how to use the csvread function in order to obtain this type of functionality?
It confuses me that there are 2 types sections. I was thinking at using the whole thing as a string and then split it into 2 .csv files and then read the corresponding line line.

Answer 1

try using this function :
I assumed that all tables have equal number of columns/rows. The code can definitely be shortened / improved / extended ;)
function multi_table_csvread (row_index)
filename_INPUT = 'multi_table.csv' ;
filename_OUTPUT = 'selected_row.csv' ;
fIN = fopen(filename_INPUT,'r');
nextLine = fgetl(fIN);
tableIndex = 0;
tableLine = 0;
csvTable = [];
% start reading the csv file, line by line
while nextLine ~= -1
lineStr = strtrim(strsplit(nextLine,',')) ;
% remove empty cells
lineStr(cellfun('isempty',lineStr)) = [] ;
tableLine = tableLine + 1 ;
% if 1 element start new table
if numel(lineStr) == 1
tableIndex = tableIndex + 1;
tableLine = 1;
csvTable{tableIndex,tableLine} = lineStr ;
else
lineStr = add_comas(lineStr) ;
csvTable{tableIndex,tableLine} = lineStr ;
end
nextLine = fgetl(fIN);
end
fclose(fIN);
fOUT = fopen(filename_OUTPUT,'w');
if row_index > size(csvTable,2) -2
error('The row index exceeds the maximum number of rows!')
end
for k = 1 : size(csvTable,1)
title = csvTable{k,1};
columnHeaders = csvTable{k,2};
selected_row = csvTable{k,row_index+2};
fprintf(fOUT,'%s\n',title{:});
fprintf(fOUT,'%s',columnHeaders{:});
fprintf(fOUT,'\n');
fprintf(fOUT,'%s',selected_row{:});
fprintf(fOUT,'\n');
end
fclose(fOUT);
function line_with_comas = add_comas(this_line)
for ii = 1 : length(this_line)-1
this_line{ii} = strcat(this_line{ii},',') ;
end
line_with_comas = this_line ;