How to edit an entire column of a text file using MATLAB?

Hi,

I have text file consist of a node and element connectivity data, with a specific phyiscal property value assigned to each element. I need to change these physical values for every element.

I have attached a sample text file. Precisely, I need to change the values of 'Kxx' and 'Kyy' column.

Is there any way to do this?

[Image Analyst]

What does each column represent (what columns are Kxx and Kyy)?

What do you want to change their values TO?

[Salman Zafar]

Kxx and Kyy represnets permeability in x and y directions. I want to change their values from 1e-11 to 1e-10. In the attached text file, Kxx is the column 13 and Kyy is coulmn 15.

[Walter Roberson]

The easiest way is treat the headers as text to be copied, and to read the rest as a numeric array that you read in as numbers, make numeric changes to, and then export as text.

[Mathieu NOE]

you can simply use any text editor and use the "replace" function

using matlab for that is just overkill

[Salman Zafar]

Actually I need to perform flow analysis on 100 different values of Kxx and Kyy between 1e-11 and 1e-10. So I was thinking to somehow use for loop for this. But I dont know how to do it on data available in text file format.

[Mathieu NOE]

sorry, I don't follow

I thought you wanted to change values (in 100 files ? ) , but now you mention I need to perform flow analysis on 100 different values of Kxx and Kyy between 1e-11 and 1e-10

it's not really the same , or ? analysis vs. replacement ??

Answer 1

[Priyanka Rai]

It is easier to edit files by code. So, if it is possible to hold a file in memory, you can load it to a MATLAB variable, make the required edits, and write back out.

You can read the entire text file using fileread/ readlines and read the parameters separately using readtable. You can then modify the values in the table and write back out.

Text files are sequential, so processing columns basically is easier in memory.

You can also check this readfile function from the FEX (also works pre- MATLAB R2020b).