How to get two arrays from .txt file?

Hi, I have a problem with getting two arrays from one file. I even have a problem with getting only one, sadly.

I don't know how to skip the text and what to do with '...'. I cannot modify the file in any way.

I need to get two arrays and later use them to display some graphs.

I was looking through many threads here but no solution works.

Answer 1

[Stephen23]

MATLAB does not have ragged arrays, you could import them as vectors, e.g.:

format short G
str = fileread('arrays2.txt');
tmp = regexp(str,'=\[[^\]]+','match');
tmp = regexp(tmp,'\d+\.?\d*','match');
out = cellfun(@str2double,tmp,'uni',0)

out = 1×2 cell array
    {[0 0.000424 0.000847 0.001271 0.001694 0.002118 0.002541 0.002965 0.003812 0.004659 0.005082 0.005929 0.006776 0.009318 0.010588 0.012282 0.013129 0.013976 0.0144]}    {[0 1693.2 2944.7 4417 6625.5 6331.1 6478.3 6183.8 6625.5 7214.5 7435.3 7729.8 8024.3 8466 8613.2 8466 8024.3 6920 5889.4]}

out{:}

ans = 1×19

0 0.000424 0.000847 0.001271 0.001694 0.002118 0.002541 0.002965 0.003812 0.004659 0.005082 0.005929 0.006776 0.009318 0.010588 0.012282 0.013129 0.013976 0.0144

ans = 1×19

1.0e+00 * 0 1693.2 2944.7 4417 6625.5 6331.1 6478.3 6183.8 6625.5 7214.5 7435.3 7729.8 8024.3 8466 8613.2 8466 8024.3 6920 5889.4

[Mikolaj Rebacz]

That's great and elegant solution, thank you!

[Stephen23]

"One question - I don't fully understand '=\[[^\]]+'. I know that we seek sentences starting with '=[' and ending with ']'. I don't know though why do we need '^', as per documentation it's supposed to seek the beginnings of sentences (and we are looking at the bracket on the end of it) and also why do we need '+' as we only have one ']' bracket at the end of each sentence?"

That regular expression matches text starting with '=[' and keeps matching any text that is not ']' (that is the actual purpose of the '^' operator), incuding all digits, spaces, newlines, etc.... anything that is not a closing square bracket, one or more times (that is the purpose of the '+' operator). That way we can get the entire content between the square brackets (if you look at its output you will also notice that it matches the opening bracket but not the closing bracket).

Broken down into its main consituent parts:

'=\[[^\]]+'
 =\[         match literal text '=['
    [   ]    match a set of characters
     ^       not equal to
      \]     match literal text ']'
         +   one or more times

For an explanation of the [] character set and the ^ syntax, see "Metacharacters" here:

https://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html#f0-42723

Answer 2

[David Hill]

Why not just copy and paste?

dL1=[0	0.000424	0.000847	0.001271	0.001694...
	0.002118	0.002541	0.002965	0.003812...
	0.004659	0.005082	0.005929	0.006776...
	0.009318	0.010588	0.012282	0.013129...
	0.013976	0.0144];
F1=[0	1693.191	2944.681	4417.021	6625.532...
	6331.064	6478.298	6183.83	        6625.532	7214.468...
	7435.319	7729.787	8024.255	8465.957...
	8613.191	8465.957	8024.255	6920  		5889.362];

[Mikolaj Rebacz]

Unfortunately I have to input it via program.

But thanks anyway

Answer 3

[Benjamin Thompson]

textscan can handle it if you read line by line:

>> fin = fopen('arrays2.txt', 'rt')

fin =

4

>> fgets(fin)

ans =

'

'

>> fgets(fin)

ans =

'randomtext:

'

>> fgets(fin)

ans =

'

'

>> S1 = fgets(fin)

S1 =

'dL1=[0 0.000424 0.000847 0.001271 0.001694...

'

>> C = textscan(S1, 'dL1=[%f %f %f %f...')

C =

1×4 cell array

{[0]} {[4.2400e-04]} {[8.4700e-04]} {[0.0013]}

[Mikolaj Rebacz]

That's interesting, unfortunately it would be a big hassle to retrieve parts of the vectors and put them together. But thank you :)