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How to optimize code/avoid a loops

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Nik Rocky
Nik Rocky on 25 Jun 2020
Commented: darova on 29 Jun 2020
I have terrible knowledge of cell arrays and I realized some loops to read and comparing the cell arrays.
If I use big arrays — calculating for every loop takes up to minute for every dataset. It's very inefficient. So, I try to describe my code part:
I have multiple cell-arrays, and I'm read while any time point t_ref_cnt the frequency values in cell M_interpl and Traj_interpl.
If the right time position is chosen, I'm writing values to from M_interpl to motor_actual and Traj_interpl to motorspeed_detected arrays.
After this operation, I have while every t_ref_cnt two Arrays that I can compare (by TP-FN-FP).
Structure of M_interpl is:
1×5 cell array with 1 x 3001 doubles
1. cell is a time t_ref_cnt 0 0,01 0,02 0,03 ... 30,0
2.,3.,4.,5. cells are frequency from 0 to x
Structure of Traj_interpl (depending on of dataset):
example 1×184 cell array with y x 2 doubles (1<y<1000)
1. cell is a time t_ref_cnt 0,03 0,04 0,05 (just small time blocks - not from 0 to 30)
2. cell are frequencys from 1 to 500
I have atatsched both files for example
for t_ref_cnt = 1:length(t_ref) %for every 10ms time step
for m_interpl_cnt = 2:length(M_interpl) %for any motor-array
for m_row_cnt = 1:length(M_interpl{m_interpl_cnt}) %for any row of single motor
if t_ref(t_ref_cnt) == M_interpl{1}(m_row_cnt) %if right row of motor is choosen
motor_actual(m_interpl_cnt-1) = M_interpl{m_interpl_cnt}(m_row_cnt); %write actual value of motorspeed to array
motor_actual(m_interpl_cnt-1) = 0;
for traj_cnt = 1:length(Traj_interpl) %for every Traj-Cell
for t_row_cnt = 1:length(Traj_interpl{traj_cnt}) %for any row of Traj
if t_ref(t_ref_cnt) == Traj_interpl{traj_cnt}(t_row_cnt,1) %if right row of Traj is choosen
motorspeed_detected(traj_cnt) = Traj_interpl{traj_cnt}(t_row_cnt,2); %write detected value to array
motorspeed_detected(traj_cnt) = 0;
I think there are a better way to solve it!?
Thank you very much in advice!
For better understanding:


darova on 28 Jun 2020
I dont' understand the question. Can you collaborate?
Here is how M_interpl looks
Here is Traj
Can you explain what are you trying to interpolate?
Nik Rocky
Nik Rocky on 28 Jun 2020
Hello Darova,
Thanks for your response!
Values of Traj in your graph can be right — you see a lot of “detections” on 120 Hz — this is a second harmonic of Ground truth M_interpl (61,4 · 2) (in this case there are no True Positive values — depending on you count just F0 or F1).
Data of Traj_interpl is already interpolated on the same x-axis (time).
(I see, I uploaded a not interpolated Traj before, here is a right one)
The question is not about interpolation — question is about — is it possible to replace loops (that takes too much time while searching inside all cells for right value) with one MATLAB function?
Thank you!
darova on 29 Jun 2020
  • The question is not about interpolation
Well, maybe you should take a look into it. You have some data (time and value) and want to have some values having time1. interp1 can easily handle this task

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