while using interp1 for matrix type data the following error found

Error using griddedInterpolant The grid vectors must contain unique points.

Error in interp1 (line 161) F = griddedInterpolant(X,V,method);

Error in sample1 (line 40) thr_new(j,:) = interp1(trq(j,:),thr,trq_new,'linear','extrap')

Answer 1

[KSSV]

thr_new = zeros(17,13) ;
mf_new = zeros(17,13) ;
new_mf_trq = zeros(17,13) ;
for  j = 1:17
    [C1,ia1,ib1] = unique(trq(j,:)) ;
    thr_new(j,:) = interp1(C1,thr(ia1),trq_new,'linear','extrap') ;

      mf_new(j,:)= interp1(thr,mf(j,:),trq_new,'linear','extrap') ;
      new_mf_trq(j,:) = interp1(thr_new(j,:),mf_new(j,:),trq_new,'linear', 'extrap') ;% new mf values corr. to new torq value
  end

[Lohith k j]

hello sir, i have following data thr = [0 10 20 30 40 50 60 70 80 90 100]; % throttle trq_new = [0 10 20 30 40 50 60 70 80 90 100 110 120]; % new torque trq = [0 0.1 29.9 87.6 99.8 101 105.6 105.4 106.1 110 120; 0 0.1 22.8 85.6 105.2 107 110 110.5 110.3 110.31 110.4; 0 0.1 17 80.6 106.1 110 112.01 112.02 112.03 112.2 112; 0 0.1 22 82.8 106 108 108.5 110 109 110 109; 0 0.1 16 79 105 110 114 114.01 113 113.01 114; 0 0.1 16.9 82.4 108 115 120.5 120.501 120.3 120.301 120.7; 0 0.1 11.4 72 105.5 115.2 120.3 120.8 120.8 120.7 120.8; 0 0.1 9 68 103.8 112.5 115.8 115.801 116.4 116 116.4; 0 0.1 6.5 63.2 103.8 109.8 111.6 111.8 111.2 112 111.8; 0 0.1 3.1 58.7 102.3 110 110.2 110.4 110.5 110.3 110.5; 0 0.1 0.2 54.6 100.5 108.6 109.5 109.6 109.601 109.602 109.3; 0 0.1 0.2 49.3 98.1 107.2 108.5 108.501 108.502 108.503 108.504; 0 0.1 0.2 47.4 95.9 106.2 107.4 107.6 107.7 107.6 107.601; 0 0.1 0.2 44.8 94.2 104 105.7 105.8 106 106.1 106.101; 0 0.1 0.2 39.4 90.1 102.4 104.5 104.501 104.6 104.601 104.602; 0 0.1 0.2 35.8 86.4 100 102.4 102.2 102.201 102.4 102.3; 0 0.1 0.2 33 83.5 97.3 100.1 100 100.1 99.5 99;]; %torq value mf = [0.1 0.11 0.49 1.1 1.28 1.32 1.53 1.54 1.53 1.54 1.55; 0 0.11 0.5 1.22 1.5 1.52 1.78 1.77 1.79 1.78 1.77; 0 0.1 0.47 1.28 1.66 1.72 2.01 2.011 1.99 2 2.01; 0 0.14 0.6 1.46 1.82 1.93 2.22 2.23 2.24 2.22 2.2; 0 0 0.6 1.56 2.03 2.14 2.53 2.52 2.54 2.55 2.54; 0 0 0.69 1.79 2.31 2.43 2.85 2.86 2.85 2.851 2.852; 0 0 0.63 1.74 2.45 2.75 3.12 3.11 3.1101 3.1102 3.12; 0 0 0.66 1.8 2.59 2.9 3.19 3.18 3.201 3.202 3.203; 0 0 0.64 1.84 2.83 3.02 3.25 3.29 3.3 3.8 3.3; 0 0 0.66 1.88 2.98 3.23 3.58 3.58 3.6 3.56 3.58; 0 0 0.65 1.91 3.12 3.42 3.83 3.8301 3.8302 3.84 3.82; 0 0 0.1 1.92 3.26 3.6 4.04 4.0401 4.05 4.04 4.05; 0 0 0.1 1.99 3.42 3.83 4.29 4.3 4.301 4.302 4.29; 0 0 0.1 2.05 3.64 4 4.53 4.5301 4.54 4.55 4.52; 0 0 0.1 2.01 3.74 4.22 4.74 4.75 4.76 4.75 4.74; 0 0 0.1 2.01 3.78 4.45 4.89 4.8901 4.8901 4.88 4.89; 0 0 0.1 2.02 3.83 4.61 4.95 4.97 4.96 4.97 4.97;]; %fuel value i need to find the "new throttle" value from thr,trq_new, and trq value tables using interpolation and also i need to find the "new_mf" from mf, new throttle,trq_new values using interpolation. please help me

Answer 2

[KSSV]

Let x, y be your x and y data.

[xx,ia,ic] = unique(x,'legacy')
yy =  y(ia) ;

Now use interp1 on xx and yy

Answer 3

[Lohith k j]

clc
thr = [0 10 20 30 40 50 60 70 80 90 100]; % throttle
trq_new = [0 10 20 30 40 50 60 70 80 90 100 110 120]; % new torq
trq = [0 0.1 29.9 87.6 99.8 101 105.6 105.4 106.1 110 120;
      0 0.1 22.8 85.6 105.2 107 110 110.5 110.3 110.3 110.4;
     0 0.1 17 80.6 106.1 110 112 112 112 112.2 112;
     0 0.1 22 82.8 106 108 108.5 110 109 110 109;
     0 0.1 16 79 105 110 114 114 113 113 114;
     0 0.1 16.9 82.4 108 115 120.5 120.5 120.3 120.3 120.7;
     0 0.1 11.4 72 105.5 115.2 120.3 120.8 120.8 120.7 120.8;   
     0 0.1 9 68 103.8 112.5 115.8 115.8 116.4 116 116.4;
     0 0.1 6.5 63.2 103.8 109.8 111.6 111.8 111.2 112 111.8;
     0 0.1 3.1 58.7 102.3 110 110.2 110.4 110.5 110.3 110.5;
     0 0.1 0.2 54.6 100.5 108.6  109.5 109.6  109.6 109.6  109.3;
     0 0.1 0.2 49.3 98.1 107.2 108.5 108.5 108.5 108.5  108.5;
     0 0.1 0.2 47.4 95.9 106.2 107.4 107.6 107.7 107.6  107.6;
     0 0.1 0.2 44.8 94.2 104 105.7 105.8 106 106.1 106.1;
     0 0.1 0.2 39.4 90.1 102.4 104.5 104.5  104.6 104.6 104.6;
     0 0.1 0.2 35.8 86.4 100 102.4 102.2 102.2  102.4 102.3;
     0 0.1 0.2 33 83.5 97.3 100.1 100 100.1 99.5 99;]; %torq value
 mf = [0.1 0.11 0.49 1.1 1.28 1.32 1.53 1.54 1.53 1.54 1.55;
      0 0.11 0.5 1.22 1.5 1.52 1.78 1.77 1.79 1.78 1.77;
      0 0.1 0.47 1.28 1.66 1.72 2.01 2.01 1.99 2 2;
      0 0.14 0.6 1.46 1.82 1.93 2.22 2.23 2.24 2.22 2.2;
      0 0 0.6 1.56 2.03 2.14 2.53 2.52 2.54 2.55 2.54;
      0 0 0.69 1.79 2.31 2.43 2.85 2.86 2.85 2.85 2.85;
      0 0 0.63 1.74 2.45 2.75 3.12 3.11 3.11 3.11 3.12;
      0 0 0.66 1.8 2.59 2.9 3.19 3.18 3.2 3.2 3.2;
      0 0 0.64 1.84 2.83 3.02 3.25 3.29 3.3 3.8 3.3;
      0 0 0.66 1.88 2.98 3.23 3.58 3.58 3.6 3.56 3.58;
      0 0 0.65 1.91 3.12 3.42 3.83 3.83 3.83 3.84 3.82;
      0 0 0.1 1.92 3.26 3.6 4.04 4.04 4.05 4.04 4.05;
      0 0 0.1 1.99 3.42 3.83 4.29 4.3 4.3 4.3 4.29;
      0 0 0.1 2.05 3.64 4 4.53 4.53 4.54 4.55 4.52;
      0 0 0.1 2.01 3.74 4.22 4.74 4.75 4.76 4.75 4.74;
      0 0 0.1 2.01 3.78 4.45 4.89 4.89 4.89 4.88 4.89;
      0 0 0.1 2.02 3.83 4.61 4.95 4.97 4.96 4.97 4.97;]; %mf
    for  j = 1:17
        ++j;
thr_new(j,:) = interp1(trq(j,:),thr,trq_new,'linear','extrap')

mf_new(j,:)= interp1(thr,mf(j,:),trq_new(j,:),'linear','extrap')

new_mf_trq(j,:) = interp1(thr_new(j,:),mf_new(j,:),trq_new,'linear', 'extrap')% new mf values corr. to new torq value
end

Answer 4

[Image Analyst]

interp1() is meant for vectors, not matrices.

Why are you trying to use a matrix?

Use interp2() or scatteredInterpolant() or griddedInterpolant() instead.

[Stephen23]

"interp1() is meant for vectors, not matrices."

Where is this stated? The interp1 documentation that I can find states that "If v is a matrix or an array, then each column contains a separate set of 1-D values", and has worked perfectly on matrices every time I have used it.