How do I perform a formatted read on exponential data?

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Matthew Koebbe
Matthew Koebbe 2022-10-26
移动：Rik 2022-10-27
I want to read a few hundred thousand lines of data. Here are the first few lines:
TABLED1 1
+ 0.000+0-0.000+0 1.000-2-3.297+1 2.000-2-4.924+1 3.000-2-5.692+1+
+ 4.000-2-1.301+2 5.000-2-1.128+2 6.000-2-1.031+2 7.000-2-9.388+1+
+ 8.000-2-8.941+1 9.000-2-9.161+1 1.000-1-9.107+1 1.100-1-9.013+1+
I've searched, read answers and tried textscan() with different options as well as some even less successful methods of reading data - all to no avail. textscan() doesn't recognize '%e' and '%f' doesn't return the desired result. I've even tried reading one line at a time and writing my own parsing algorithm. What I wouldn't give for a good Fortran read() statement! lol
Thank you in advance for your time and consideration.
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Matthew Koebbe
Matthew Koebbe 2022-10-26
Rik, As the title indicates, formatted data, namely 10 columns of 8 characters. See FORTRAN, NASTRAN, etc. You know, old folks' stuff. :) If I add spaces to make the data more readable, the first line becomes
0.000+0 -0.000+0 1.000-2 -3.297+1 2.000-2 . . .
You get the idea. This particular data format doesn't require the 'E' or 'e'.
VBBV, Thanks!
Matthew Koebbe
Matthew Koebbe 2022-10-26
移动：Rik 2022-10-27
I want to thank everyone who has answered. I definitely have learned new things about MATLAB, and I look forward to working through the solutions I haven't gotten to yet. I have other work that demands my attention through COB tomorrow, but I'll give my final solution choice on Friday. Thanks again!

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回答（2 个）

Rik
Rik 2022-10-26
编辑：Rik 2022-10-26
Ran in:
Edit at the top: You can get the data in this format with my readfile function, or with data=cellstr(readlines(filename));.
There are perhaps more direct ways, but this is how you can do it with a regular expression.
data={'+ 0.000+0-0.000+0 1.000-2-3.297+1 2.000-2-4.924+1 3.000-2-5.692+1+',
'+ 4.000-2-1.301+2 5.000-2-1.128+2 6.000-2-1.031+2 7.000-2-9.388+1+',
'+ 8.000-2-8.941+1 9.000-2-9.161+1 1.000-1-9.107+1 1.100-1-9.013+1+'};
tokens=regexp(data,'-?([0-9\.]+)([\+\-]\d+)','tokens')
tokens = 3×1 cell array
{1×8 cell} {1×8 cell} {1×8 cell}
tokens{1}
ans = 1×8 cell array
{1×2 cell} {1×2 cell} {1×2 cell} {1×2 cell} {1×2 cell} {1×2 cell} {1×2 cell} {1×2 cell}
output = NaN(numel(tokens),numel(tokens{1}));
for n=1:numel(tokens)
for m=1:numel(tokens{n})
tmp = str2double(tokens{n}{m});
output(n,m) = tmp(1) * 10^tmp(2);
end
end
output
output = 3×8
0 0 0.0100 32.9700 0.0200 49.2400 0.0300 56.9200 0.0400 130.1000 0.0500 112.8000 0.0600 103.1000 0.0700 93.8800 0.0800 89.4100 0.0900 91.6100 0.1000 91.0700 0.1100 90.1300
Mathieu NOE
Mathieu NOE 2022-10-26
Coming a bit too late in the show...
filename = 'tabled1.txt'
header_lines = 1;
data = get_my_data(filename,header_lines)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function data = get_my_data(filename,header_lines)
lines = readlines(filename);
data = []; % concat
for ci = 1+header_lines:numel(lines)
line = char(lines(ci));
if numel(line)>1
line = line(end-64:end-1) % keep only 8 numbers coded on 8 characters
nums_one_line = [];
for cc = 1:8
ind1 = 1+(cc-1)*8;
ind2 = ind1+7;
numb = line(ind1:ind2); % example : '-8.941+1'
% + or - for exponant is in position 7
mantissa = str2double(numb(1:6));
expo = str2double(numb(7:8));
num = mantissa*10^(expo);
nums_one_line = [nums_one_line num]; % concat
end
data = [data; nums_one_line]; % concat
end
end
end

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