Lookup values in other table that has a range of values
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Daniel Goldstein
on 14 Feb 2022
Commented: Daniel Goldstein
on 14 Feb 2022
I've got two data sets from a drilling project collected by different sensors.
One table has rate of penetration at the recorded depths. The other has wireline gamma values for the same hole but at different recorded depths.
Rate of Penetration data set
holeid = [12;12;12;12;12;12;12;12;12;12;12;12;12;12;12;12];
depth = [0;0.0542;0.0801;0.2222;0.3959;0.4572;0.5110;0.5348;0.5712;0.6099;0.6437;0.6799;0.8011;0.8928;0.9590;1.0110];
rop = [118.7000;207.8000;139.6000;176.0000;177.8000;229.3000;242.4000;138.9000;85.7000;140.8000;164.5000;125.4000;189.8000;164.0000;118.4000;211.4000];
rophole12 = table(holeid,depth,rop);
Gamma data set
(e.g. depth from 0 to 0.13 is treated as from/to range and has gamma value of 1, depth of 0.13 to 0.22 has gamma value of 12, etc)
holeid1 = [12;12;12;12;12;12;12;12;12;12;12;12;12];
depth1 = [0;0.13;0.22;0.36;0.48;0.56;0.67;0.78;0.84;0.96;1.03;1.14;1.24;];
gamma1 = [1;12;34;23;42;12;43;67;111;200;153;188;55];
gammahole12 = table(holeid1,depth1,gamma1);
What's the best way to get the gamma values from gammahole12 at the depths specified in the rophole12 table e.g. gamma at 0, 0.0542, 0.0801, etc?
In excel, I've used the vlookup function with true. Is there a MATLAB equivalent or different way to lookup a value within a different table with approximate reference, e.g. depth in this case?
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Accepted Answer
AndresVar
on 14 Feb 2022
Edited: AndresVar
on 14 Feb 2022
Something like this would add the gamma variable to your first table, BUT it's matching to nearest gamma
rophole12.gamma = interp1(gammahole12.depth1,gammahole12.gamma1,rophole12.depth,'nearest')
See: 1-D data interpolation (table lookup) - MATLAB interp1 (mathworks.com) for other matching options such as next or previeous
2 Comments
Cris LaPierre
on 14 Feb 2022
Using 'previous' seems to give the same results as vlookup.
holeid = [12;12;12;12;12;12;12;12;12;12;12;12;12;12;12;12];
depth = [0;0.0542;0.0801;0.2222;0.3959;0.4572;0.5110;0.5348;0.5712;0.6099;0.6437;0.6799;0.8011;0.8928;0.9590;1.0110];
rop = [118.7000;207.8000;139.6000;176.0000;177.8000;229.3000;242.4000;138.9000;85.7000;140.8000;164.5000;125.4000;189.8000;164.0000;118.4000;211.4000];
rophole12 = table(holeid,depth,rop);
holeid1 = [12;12;12;12;12;12;12;12;12;12;12;12;12];
depth1 = [0;0.13;0.22;0.36;0.48;0.56;0.67;0.78;0.84;0.96;1.03;1.14;1.24;];
gamma1 = [1;12;34;23;42;12;43;67;111;200;153;188;55];
gammahole12 = table(holeid1,depth1,gamma1);
% Use interp1 with method set to 'previous' to get same result as vlookup
% (for this example, at least)
rophole12.gamma = interp1(gammahole12.depth1,gammahole12.gamma1,rophole12.depth,'previous')
More Answers (1)
Cris LaPierre
on 14 Feb 2022
Edited: Cris LaPierre
on 14 Feb 2022
% Recreate your tables
holeid = [12;12;12;12;12;12;12;12;12;12;12;12;12;12;12;12];
depth = [0;0.0542;0.0801;0.2222;0.3959;0.4572;0.5110;0.5348;0.5712;0.6099;0.6437;0.6799;0.8011;0.8928;0.9590;1.0110];
rop = [118.7000;207.8000;139.6000;176.0000;177.8000;229.3000;242.4000;138.9000;85.7000;140.8000;164.5000;125.4000;189.8000;164.0000;118.4000;211.4000];
rophole12 = table(holeid,depth,rop);
holeid1 = [12;12;12;12;12;12;12;12;12;12;12;12;12];
depth1 = [0;0.13;0.22;0.36;0.48;0.56;0.67;0.78;0.84;0.96;1.03;1.14;1.24;];
gamma1 = [1;12;34;23;42;12;43;67;111;200;153;188;55];
gammahole12 = table(holeid1,depth1,gamma1);
% Use discretize to find the corresponding 'bin' gamma value
rophole12.gamma = discretize(rophole12.depth,[gammahole12.depth1;inf],gammahole12.gamma1)
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