Efficient way of extracting parameters from a text file without external utilities

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Jyotish Robin 2019-7-9

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https://ww2.mathworks.cn/matlabcentral/answers/470937-efficient-way-of-extracting-parameters-from-a-text-file-without-external-utilities

回答： Abhilash Padma 2019-7-17

采纳的回答： Abhilash Padma

I have a txt file whose content is as follows (There are around 1000,000 rows).

Basically there are 4 parameters, each of which can take non-negative integer values:

type 0,val1
type 0,val2
type 1,val1
type 1,val2

I need to extract their values and form 4 arrays one for each parameters. . How can I do this in a time efficient way?

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Walter Roberson 2019-7-9

This belongs as part of https://www.mathworks.com/matlabcentral/answers/470798-fastest-way-to-create-arrays-programmatically-for-particular-parameter-values-from-a-set-of-text-fi

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Answer 1

Abhilash Padma 2019-7-17

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https://ww2.mathworks.cn/matlabcentral/answers/470937-efficient-way-of-extracting-parameters-from-a-text-file-without-external-utilities#answer_383529

Hi,

I understand that there is a text file which contains different values belongs to any of the 4 types.

They are:

type 0, val1 ; type 0, val2 ; type 1, val1 ; type 1, val2

You need to read all the values and store them in 4 variables where each variable belongs to different datatypes.

Try the following code, which should work for your problem.

str=fileread('test.txt'); 
var1=str2double(regexp(str, '(?<=type\s+0,val1\s+=\s+)\w*', 'match')); 
var2=str2double(regexp(str, '(?<=type\s+0,val2\s+=\s+)\w*', 'match')); 
var3=str2double(regexp(str, '(?<=type\s+1,val1\s+=\s+)\w*', 'match')); 
var4=str2double(regexp(str, '(?<=type\s+1,val2\s+=\s+)\w*', 'match')); 