This question is related to How can I merge this data in MATLAB?
how to use the FIND
function with IF
statement? eg if I have this data:
20 10 1
20 11 1
20 15 1
23 10 1
23 10 1
23 12 0
Rule 1: Data of column 3 must be 1.
Rule 2: If n
is the current index of column 1, if n
equal n-1
(20=20) of column 1, data of column 2 of index n and n-1 is merged.
20 21 0
20 15 0
20 0 0
23 20 0
23 0 0
23 12 0
EDITED:
fid=fopen('data.txt');
A=textscan(fid,'%f%f%f');
fclose(fid);
in = cell2mat(A)'; %'# fix for SO formatting - Jonas
%# rows2mergeFrom are the rows where the second row equals the first row of col 1
%# and where the third column is 1. rows2mergeInto indicates the rows from which the
%# values of the following rows should be added
rows2mergeFrom = find(in(2:end,1) == in(1:end-1,1) & in(2:end,3) == 1) + 1;
out = in;
out(rows2mergeFrom-1,2) = out(rows2mergeFrom-1,2) + out(rows2mergeFrom,2);
%# data that has been shifted up gets subtracted from the 'rows2mergeFrom'-rows
out(rows2mergeFrom,2) = out(rows2mergeFrom,2) - in(rows2mergeFrom,2);
%# remove the ones in the third column from any row that has been involved in a
%# merge operation
out([rows2mergeFrom;rows2mergeFrom-1],3) = 0
fid = fopen('newData.txt','wt');
format short g;
fprintf(fid,'%g\t %g\t %g\n',out); %'# Write the data to the file
fclose(fid);
There is no need for an if-statement. What you need is a logical array that allows find
to extract the row indices of the rows that are to be merged.
Updated to conform with the new rules
in = [20 10 1
20 11 1
20 15 1
23 10 1
23 10 1
23 12 0];
%# rows2mergeFrom are the rows where the second row equals the first row of col 1
%# and where the third column is 1. rows2mergeInto indicates the rows from which the
%# values of the following rows should be added
rows2mergeFrom = find(in(2:end,1) == in(1:end-1,1) & in(2:end,3) == 1) + 1;
out = in;
out(rows2mergeFrom-1,2) = out(rows2mergeFrom-1,2) + out(rows2mergeFrom,2);
%# data that has been shifted up gets subtracted from the 'rows2mergeFrom'-rows
out(rows2mergeFrom,2) = out(rows2mergeFrom,2) - in(rows2mergeFrom,2);
%# remove the ones in the third column from any row that has been involved in a
%# merge operation
out([rows2mergeFrom;rows2mergeFrom-1],3) = 0
out =
20 21 0
20 15 0
20 0 0
23 20 0
23 0 0
23 12 0
As far as I can tell, you don't need to use find or if. You only need logical indexing.
If I understand your question correctly, Amro is right in pointing out that your output doesn't match your description of the logic. Try the following script:
m = [20 10 0; ...
20 11 0; ...
20 15 1; ...
23 10 1; ...
23 10 1];
merge = (m(1:end-1, 1) == m(2:end, 1)) & (m(2:end,3) == 1)
mnew = m(2:end, :);
madd = m(1:end-1,2) + m(2:end,2);
mnew(merge, 2) = madd(merge);
mnew = [m(1,:); mnew]
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