How to fasten the loop

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Arun Kumar Singh
Arun Kumar Singh 2022-9-22
评论： Rik 2022-9-22
for i=1:size(LAT1)-1
disp(i);
if ((Time1(i+1)-Time1(i)==1)&& (strcmp(SAT1(i),SAT1(i+1))) && (strcmp(ST1(i),ST1(i+1))) && (strcmp(COMB1(i),COMB1(i+1))) )
Long{k}(j,1)=Long1(i);
LAT{k}(j,1)=LAT1(i);
STEC{k}(j,1)=STEC1(i);
VTEC{k}(j,1)=VTEC1(i);
ELV{k}(j,1)=ELV1(i);
Time{k}(j,1)=Time1(i);
SAT{k}(j,1)=SAT1(i);
ST{k}(j,1)=ST1(i);
COMB{k}(j,1)=COMB1(i);
j=j+1;
else
k=k+1;
j=1;
end
end
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Torsten
Torsten 2022-9-22
Don't you always forget to put Long1(i), LAT1(i),..., COMB1(i) in the new cell array Long{k+1}(1,1),LAT{k+1}(1,1),...,COMB{k+1}(1,1) if the if-condition is false ?
I mean: Imagine the if-condition is false for all i - then the cell arrays Long, LAT,...,COMB would be empty.
Arun Kumar Singh
Arun Kumar Singh 2022-9-22
No i do not need those values when condition becomes false.

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回答（1 个）

Torsten
Torsten 2022-9-22
编辑：Torsten 2022-9-22
Ran in:
Maybe there are faster commands than arrayfun for extracting the elements of LONG in cell arrays that correspond to sequences of zeros in the logical i array, but I couldn't find an efficient ad hoc solution for this.
Maybe MATLAB experts can help here.
TIME = [1 2 3 4 5];
SAT1 = ["a","aa","aa","aa","aa"];
ST1 = SAT1;
COMB1 = SAT1;
n = numel(TIME);
I1 = diff(TIME) == 1
I1 = 1×4 logical array
1 1 1 1
I2 = strcmp(SAT1(1:n-1),SAT1(2:n))
I2 = 1×4 logical array
0 1 1 1
I3 = strcmp(ST1(1:n-1),ST1(2:n))
I3 = 1×4 logical array
0 1 1 1
I4 = strcmp(COMB1(1:n-1),COMB1(2:n))
I4 = 1×4 logical array
0 1 1 1
I = (~I1) | (~I2) | (~I3) | (~I4)
I = 1×4 logical array
1 0 0 0
edges = [find(I == 1),n]
edges = 1×2
1 5
LONG1 = [3 10 12 4 8]
LONG1 = 1×5
3 10 12 4 8
LONG = arrayfun(@(i)LONG1(edges(i)+1:edges(i+1)-1),1:numel(edges)-1,'UniformOutput',0)
LONG = 1×1 cell array
{[10 12 4]}
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Torsten
Torsten 2022-9-22
编辑：Torsten 2022-9-22
The contiguous parts of the array LONG1 should be extracted that belong to the contiguous parts where the I array is false.
I = [true false false true true false true]
should extract
LONG{1} = [LONG1(2),LONG1(3)]
LONG{2} = [LONG1(6)]
Rik
Rik 2022-9-22
Perhaps Jan's RunLength function will be helpful to see how to split the contiguous parts efficiently.
Otherwise, ~I should be a good start: you would only have to split that based on the run length of false, for which you could use mat2cell.

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