Getting distance between specific numbers in array after using diff() function
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I would like to find a distance between specific arrays (this distance represents time), I got it as an output of using diff function thanks to it I know when foot movement started. For example let's say I have array like this:
x = [ 0 1 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 1 0 0 0 -1]
And I would like to automate the code and find the distance - how many zeros are between 1 and -1 (i don't want from -1 and 1), So for example from this code I'd know that I have 1) 10 zeros space between first 1 and -1 and index range between first and last zero, and for the 2) 3 zeros space and also indexes. Is that possible to do?
采纳的回答
x = [0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 1, 0, 0, 0, -1];
pos = find(x == 1);
neg = find(x == -1);
len = neg - pos - 1
If the trailing -1 is missing:
len = neg(1:numel(pos)) - pos - 1;
5 个评论
M
2022-6-12
Jan
2022-6-13
What is an "index range"? Please post exactly, which output you need.
Image Analyst
2022-6-13
I assume it's like in my answer below where I give the starting and ending index for each run of zeros.
Jan
2022-6-14
Thanks. So starting is at pos+1 and ending at neg-1.
x = [0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 1, 0, 0, 0, -1];
pos = find(x == 1);
neg = find(x == -1);
len = neg - pos - 1
% Find out where each run of 0's start and end>
startingPositions = pos + 1
endingPositions = neg - 1
It seems to miss the zero starting and ending at index 1, and the run starting at 14 and ending at 16.
Maybe search for the zeros directly instead of for 1 and -1.
更多回答（1 个）
If you have the Image Processing Toolbox you can use regionprops to find the location of the "0" regions:
x = [ 0 1 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 1 0 0 0 -1];
props = regionprops(x == 0, 'Area', 'PixelIdxList');
allZeroLengths = [props.Area]
for k = 1 : numel(props)
startingIndexes(k) = props(k).PixelIdxList(1);
endingIndexes(k) = props(k).PixelIdxList(end);
end
startingIndexes % Show in command window
endingIndexes
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