How to find values in a table

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Poseidon 2023-11-4

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https://ww2.mathworks.cn/matlabcentral/answers/2043007-how-to-find-values-in-a-table

编辑： Poseidon 2023-11-5

采纳的回答： Walter Roberson

Hi,

I have a question, lets say I have a table like this

In matlab I want to find/call a value in column 3 corresponding to say 100 in first column. Not only that, but I also want to use values not in the table (say for 95 in the first column) using linear interpolation. I want to be able to do this using any of the columns. How can I achieve this in MATLAB? Please help.

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采纳的回答

Walter Roberson 2023-11-4

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https://ww2.mathworks.cn/matlabcentral/answers/2043007-how-to-find-values-in-a-table#answer_1346702

在 MATLAB Online 中打开

%let your table be named T
column_with_key = 1;
column_to_examine = 3;
value_to_lookfor = 100;
value_to_extrapolate = 95;
mask = T.(column_with_key) == value_to_lookfor;
wanted_value1 = T.(column_to_examine)(mask)
wanted_value2 = interp1(T.(column_with_key), T.(column_to_examine), value_to_extrapolate)

In practice it is usually shorter than this, such as just

wanted_value = interp1(T.var1, T.var3, 95)

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Walter Roberson 2023-11-5

在 MATLAB Online 中打开

F = scatteredInterpolant(T.pressure, T.entropy, T.enthalpy);
interpolated_enthalpies = F(query_pressures(:), query_entropys(:));

Poseidon 2023-11-5

编辑：Poseidon 2023-11-5

Thank you! This worked. But I think I have to use the previous answer (the subset) because for some cases its giving a wrong answer (like finding the enthalpy using entropy for a pressure).

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