Importing big .ASC file

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Guglielmo Giambartolomei
评论： Guglielmo Giambartolomei 2020-8-3
Good morning, I searched on the web but I din't find anything useful for me.
I have a big .ASC file that begins like this:
Time 1 - default sample rate [s] MX840A_0_CH 1 [µm/m] MX840A_0_CH 2 [µm/m] MX840A_0_CH 3 [µm/m] MX840A_0_CH 4 [µm/m] MX840A_0_CH 5 [µm/m] MX840A_0_CH 6 [µm/m] MX840A_0_CH 7 [µm/m] MX840A_0_CH 8 [µm/m] Time 2 - default sample rate [s] Time 2 - fast sample rate [s] MX410_0_CH 1 [µm/m] MX410_1_CH 2 [g]
0 0,1980 0,3258 -0,2376 -0,5230 1,680 -0,1286 -0,3765 -0,2802 0 0 0,2373 -0,00105
0,00083 0,07124 0,3033 -0,04901 -0,4132 1,524 0,05268 -0,2449 -0,1356 0,00083 0,00021 0,2639 -0,00067
0,00167 0,05543 0,2692 0,05971 -0,3727 1,215 0,2908 -0,1258 -0,1223 0,00167 0,00042 0,3119 0,000
0,00250 0,1738 0,2790 0,2098 -0,3734 0,7158 0,1389 -0,1260 -0,1299 0,00250 0,00063 0,3839 0,00058
0,00333 0,2204 0,2843 0,3669 -0,2345 0,3564 0,09048 0,01820 -0,04594 0,00333 0,00083 0,3732 0,00080
...
It is basically n x 13 matrix with a big "n" (millions of rows).
I would like to import all these data in a suitable file for Matlab. I tried with the code:
filename = 'myfile01.txt';
delimiterIn = ' ';
headerlinesIn = 1;
A = importdata(filename,delimiterIn,headerlinesIn);
The result of this simple script (A) is only a 1x1 cell. I can't understand what I am missing. I would like to handle this data in Matlab then, in order to perform an analysis.
Thank you for your help!
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Guglielmo Giambartolomei
Guglielmo Giambartolomei 2020-7-30
@Ive Ive: no, I didn't try. Thanks!
Guglielmo Giambartolomei
Guglielmo Giambartolomei 2020-7-30
@Walter Roberson: I'm able to read the text file with the Matlab button "Import data" on the top of the window but it's very slow on my computer.

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Walter Roberson
Walter Roberson 2020-7-30
T = readtable('big.ASC','filetype','text', 'decimal', ',');
(I'm not sure why it loses the variable names.)
When I copy and paste from what you posted, I end up with an empty 14th column, indicating that there is a tab after the 13th column. You can do
T{:,1:13}
to extract a numeric array of 13 columns, or you can
T(:,14:end) = [];
to delete anything after column 13.
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Guglielmo Giambartolomei
Guglielmo Giambartolomei 2020-7-31
R2018b Walter. Thank you!
Walter Roberson
Walter Roberson 2020-7-31
I think the above code might work. I am not certain, as the sample you copyied and pasted might not have exactly the same format as your actual file. Testing would be easier if you could attach a sample as a file.

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更多回答（1 个）

Guglielmo Giambartolomei
Dear Walter, I downloaded the 2020a version and it works! I have a question: now I have a n x 1 table (one column of the T table). How can I covert that object in a n x 1 double in order to analyse the data? Thank you!
  2 个评论
Walter Roberson
Walter Roberson 2020-7-31
T{:, ColumnNumber}
or you can use table2array() but I have not found that to fit into my style.
Guglielmo Giambartolomei
Guglielmo Giambartolomei 2020-8-3
I used table2array...Thank you very much!

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