MATLAB: How to obtain data from plots

graphplotplotting

I want to get data from the plot(a,b), if i only know three points in 'a' and three points in 'b'

for an example a=[52 104 157] and b=[0.1 0.4 0.4 ] and i want to know the values of remaining points (e.g value of 'b' for 'a'= 60 etc.)

I want to get all the data points in between in a new file.

please help me with any ideas

Regards Agassi

Best Answer

Use the interp1 function to do the interpolation:

a=[52 104 157];
b=[0.1 0.4 0.4 ];
b60 = interp1(a, b, 60)

produces:

b60 =
           0.146153846153846

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MATLAB: Making a surface in 3D space with sample some irregular points

You could use the code below as a starting point. First, get rid of the commas and read in your data as follows:

p=[0.010 0.053 0.020
...
0.025 0.032 0.005];

Then find the convex hull:

K = convhull(p);

Finally, plot the surface:

trisurf(K,p(:,1),p(:,2),p(:,3))

The matrix K provides three indices in each row that define a triangle (each index refers to the appropriate row of coordinates in your data matrix). If it doesn't correspond to the surface you want, you'll probably need to create K manually.

MATLAB: I have an array of data from a sensor which varies from positive to negative continuously. I want to find the peak value of each set of positive numbers and negative numbers.

>> findpeaks(X(X>0))
ans =
  Columns 1 through 10
    4.5190    4.5260    3.3360    3.1910    2.4630    1.8080    1.7910    1.3260    1.0030    0.7530
  Columns 11 through 20
    0.5650    0.4140    0.3060    0.3030    0.2290    0.2280    0.1710    0.1710    0.1300    0.1180
  Columns 21 through 30
    0.0980    0.0740    0.0520    0.0540    0.0410    0.0410    0.0320    0.0250    0.0190    0.0200
  Columns 31 through 40
    0.0020    0.0150    0.0150    0.0150    0.0110    0.0110    0.0110    0.0110    0.0070    0.0080
  Columns 41 through 50
    0.0090    0.0090    0.0090    0.0020    0.0040    0.0070    0.0020    0.0030    0.0030    0.0040
  Columns 51 through 59
    0.0050    0.0020    0.0020    0.0030    0.0030    0.0030    0.0030    0.0020    0.0020
>> abs(findpeaks(-X(X<0)))
ans =
  Columns 1 through 10
    3.8980    3.7790    2.8760    2.1120    2.1030    1.5570    1.5540    1.1540    0.8550    0.6340
  Columns 11 through 20
    0.4610    0.4700    0.3490    0.2600    0.1950    0.1450    0.1090    0.0790    0.0810    0.0590
  Columns 21 through 30
    0.0600    0.0600    0.0450    0.0450    0.0340    0.0270    0.0270    0.0200    0.0150    0.0150
  Columns 31 through 40
    0.0150    0.0100    0.0030    0.0100    0.0100    0.0100    0.0020    0.0060    0.0060    0.0060
  Columns 41 through 50
    0.0060    0.0050    0.0040    0.0020    0.0040    0.0040    0.0040    0.0040    0.0020    0.0020
  Columns 51 through 60
    0.0020    0.0020    0.0030    0.0030    0.0020    0.0020    0.0020    0.0020    0.0020    0.0020
  Columns 61 through 64
    0.0020    0.0020    0.0020    0.0020
>>

findpeaks is in Signal Processing Toolbox...

Best Answer

Related Solutions

MATLAB: Making a surface in 3D space with sample some irregular points

MATLAB: I have an array of data from a sensor which varies from positive to negative continuously. I want to find the peak value of each set of positive numbers and negative numbers.

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