Drop column of values using if function

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Mahshad Rabiee
Mahshad Rabiee 2021-4-22
编辑： Scott MacKenzie 2021-4-22
I'm trying add some lines of code which drop columns that don't meet the condition. My values are 1500x28 matrix. Example:
if condition met
drop specific coloumn that meets condition
I know using A(:,3)=[] would drop column 3 but how do I not specify column number.
Thanks!
  2 个评论
Scott MacKenzie
Scott MacKenzie 2021-4-22
You can specify the column number as a variable. But, you'll need to set that variable to 3, perhaps through an if-else arrangement that includes the condition you allude to. More details would be helpful.
Mahshad Rabiee
Mahshad Rabiee 2021-4-22
Here is my code currently, i basically just want to ignore any columns in my plot where the percentage difference is less than 50%.
for i=1:length(mod_dirs)
%% ----------------------------------------------------MA data
% read the MomentArm (MA) data
MA_filename = [ base_dir mod_dirs{i} '\MA_MTL\' 'right_hip_muscle_flexion_MA.sto'];
MA = read_motionFile(MA_filename);
time = MA.data(:,2);
ma_flexion = MA.data(:,3:30);
ma_flexion_cm=ma_flexion*100;
mini_ma_flexion=min(ma_flexion_cm);
maxi_ma_flexion=max(ma_flexion_cm);
if (maxi_ma_flexion-mini_ma_flexion)<=(0.5*mini_ma_flexion);
ma_flexion_cm(:,:)=[];
continue;
end
[cycle_time,TN_ma_flexion]=normalise_data_points(time,ma_flexion_cm,t_cycle_start,t_cycle_end);
% create a plot of the MA of a selected muscle around the flex/ext axis
figure()
plot(cycle_time, TN_ma_flexion)

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回答（1 个）

Scott MacKenzie
Scott MacKenzie 2021-4-22
编辑：Scott MacKenzie 2021-4-22
Set up a for-loop for your code, something like this.
time = MA.data(:,2);
for i=3:30
ma_flexion = MA.data(:,i);
ma_flexion_cm=ma_flexion*100;
mini_ma_flexion=min(ma_flexion_cm);
maxi_ma_flexion=max(ma_flexion_cm);
if (maxi_ma_flexion-mini_ma_flexion)<=(0.5*mini_ma_flexion)
ma_flexion_cm(:,i)=[];
end
end
The variable i will equal the column number whenever the condition is true, and the corresponding column will be deleted. Note: I deleted the semi-colon at the end of the if-expression.
  4 个评论
显示 2更早的评论
Mahshad Rabiee
Mahshad Rabiee 2021-4-22
The for loop seems to have created just one column
Scott MacKenzie
Scott MacKenzie 2021-4-22
编辑：Scott MacKenzie 2021-4-22
Well, I said "something like this". I guess I'm not quite sure what you are trying to do. Maybe you need the loop setup like this:
ma_flexion = MA.data(:,3:30);
ma_flexion_cm=ma_flexion*100;
mini_ma_flexion=min(ma_flexion_cm); % array with 27 elements
maxi_ma_flexion=max(ma_flexion_cm); % array with 27 elements
for i=1:27
if (maxi_ma_flexion(i)-mini_ma_flexion(i))<=(0.5*mini_ma_flexion(i))
ma_flexion_cm(:,i)=[];
end
end
I think you can even do this without the for-loop. Try replacing the last five lines above with this:
conditionLogical = (maxi_ma_flexion-mini_ma_flexion)<=(0.5*mini_ma_flexion);
ma_flexion_cm(:,conditionLogical)=[];

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