ThingSpeak

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I have a data. And, I want to substract the data using for. But, I want to ignore the nan values and substract others. For example, [1, 2, 3, NaN, 6, 9, 12, 14] ---- substract---> [1, 1, 3, 3, 2] How can I do this? I want to ignore nan values and substract others. What is the expected answer? I'm not clear what you mean by subtract for arrays. [1,2,3,6,9,12,14] - [ 1,1,3,3,2] =? Here is how you can clean the nan values though: A=[1, 2, 3, NaN, 6, 9, 12, 14]; AnoNan=A(~isnan(A)); B = [1, 1, 3, 3, 2]; BnoNan=B(~isnan(B)); Thanks for your answer! I want to this. A=[1, 2, 3, NaN, 6, 9, 12, 14]; ---> B = [A(2)-A(1), A(3)-A(2), A(4)-A(3). A(5)-A(4) ....] But, There is a data including the NaN values in my loop. I want to get the rate of change of sensor data. load('data_20220716.mat'); % SOG[m/s] / COG[rad] / time[sec] data = data2{5, 1}; SOG_time_data = [data(:, 1) data(:, 3)]; COG_time_data = [data(:, 2) data(:, 3)]; threshold_SOG = 0.1; threshold_COG = 0.1; for i = 2 : 1 : length(data) if isnan(SOG_time_data(i-1, 1)) || isnan(SOG_time_data(i-1, 2)) SOG_time_data(i-1, :) = nan; elseif isnan(SOG_time_data(length(data), 1)) || isnan(SOG_time_data(length(data), 2)) SOG_time_data(length(data), :) = nan; end if isnan(COG_time_data(i-1, 1)) || isnan(COG_time_data(i-1, 2)) COG_time_data(i-1, :) = nan; elseif isnan(COG_time_data(length(data), 1)) || isnan(COG_time_data(length(data), 2)) COG_time_data(length(data), :) = nan; end % SOG_time_data_index = [find(isnan(SOG_time_data(:, 1)), 1, 'last'), 1]; % ddd_SOG_time_data(:, :) = SOG_time_data(~isnan(SOG_time_data(i, :))) - SOG_time_data(~isnan(SOG_time_data(i-1, :))); if isnan(SOG_time_data(i-1, 1)) continue else d_SOG_time_data(i-1, :) = SOG_time_data(i, :) - SOG_time_data(i-1, :); end if isnan(COG_time_data(i-1, 1)) continue else d_COG_time_data(i-1, :) = COG_time_data(i, :) -COG_time_data(i-1, :); end end The fucntion diff does that for you. A=[1, 2, 3, NaN, 6, 9, 12, 14]; AnoNan=A(~isnan(A)); AnoNanDiff= diff(AnoNan); Thx Christopher Staples! But, the index of data must not be changed Are you replacing Nan with a value then? If you leave the index constant, you wont be able to do A(4)-A(3) for A=[1, 2, 3, NaN, 6, 9, 12, 14]; nan nan value nan values calculate matlab data processing