MATLAB read formatted numbers from a file after a certain line - matlab

Question

I have a file that contains arbitrary lines of characters/numbers. I need to extract formatted number after a certain line as follows:
Start of text file
Here is arbitrary lines of characters and numbers
1 -100
2 -200
...
ABC
1 2 3
...
Start extracting the following formatted numbers after the blank line
10 1.5-04
20 -1.6-04
100 1.7-04
200 1.8-04
300 -1.9-04
400 -2.0-04
Stop reading when you find the previous blank line
Then more arbitrary lines of characters and numbers
ABC
1 2 3
Then end of file
Using MATLAB, the question is how to extract the two columns of formatted numbers starting from (10 1.5-04) to (400 -2.0-04) after reaching the line that says "Start extracting the following formatted numbers after the blank line." Note the length of this column is not known in advance.

Answer 1

I use regex to extract the numbers form your text, but I can't write a specific expression to extract the two columns because there is no such a text before and after these values can rely on.
clear
text = fileread('test_file.txt');
pattern = '(?=(\s|-)[\d]+)(-|\s)[\d]+';
%pattern = '((\s|-)[\d]+)';
out = regexp(text, pattern,'match')
I hope my code gives you an idea ^-^

Answer 2

(1) Read file line by line
(2) Find keyword to start reading after
(3) Read formatted number
(4) Leave file when done with formatted numbers
clc;close all; clear *
filename='Test.txt';
File = fopen(filename,'r');
LineCont=0; %Line counter
Flag=0; %Flag to start extracting formatted numbers
st2='Start extracting the'; %Keyword
%Read file line by line
tline = fgetl(SGDFile); %Read first line
while ischar(tline)
Lcont=Lcont+1; %Line number
k = strfind(tline,st2); %Check for keywork to start extracting
if ~isempty(k) %Start extracting numbers
Flag=1; %Flag to start reading formatted numbers
Num=[]; %Collect formatted numbers here
end
tline = fgetl(File); %Move to next line
if tline ~=-1 %If not empty
if Flag==1
value = strsplit(tline); %Split numbers and text
num= str2num(char(value))'; %Convert text to number
if size(num,1)<1 %Stop reading when blank
break %Exit loop
else
Num=[Num;num]; %Collect formatted numbers
end
end
end
end
fclose(File);
This might be an inefficient way of doing it, but it works.