How do I extract fixed-width columns from a file that includes empty spaces?

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deathtime 2022-8-16

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https://ww2.mathworks.cn/matlabcentral/answers/1780310-how-do-i-extract-fixed-width-columns-from-a-file-that-includes-empty-spaces

回答： Benjamin Thompson 2022-8-16

I have a file called gridpoints.txt. It is structured as follows:

$$ GRID Data

GRID 100 6956.519 492.02359.538

GRID 101 7366.59 492.02359.53

GRID 102 6976.51 492.02 59.538

After the single header line above, the data block segment begins, with each line in this segment beginning with "GRID". There are thousands of similar lines in the file that follow.

In this data block segment, there are 6 fixed-with columns, each 8 characters long - and this includes the empty spaces. For example, the column entries of the first data block row are:

column 1 entry: "GRID "

column 2 entry: " 100"

column 3 entry: " "

column 4 entry: "6956.519"

column 5 entry: " 492.0"

column 6 entry: "2359.538"

Essentially I am trying to capture the numbers contained in columns 4, 5 and 6 and store in cell arrays. Across all the rows, the number of empty characters within each fixed width column can vary, as can be seen in the file content sample above.

What is the most straightforward way to do this?

Thank you.

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Dyuman Joshi 2022-8-16

在 MATLAB Online 中打开

You can use str2num

%using data directly, edit according to use
x=["6956.519";"   492.0";"2359.538"];
y=cell(1,numel(x));
for i=1:numel(x)
    y{i}=str2num(x(i));
end
y
y = 1×3 cell array
    {[6.9565e+03]}    {[492]}    {[2.3595e+03]}

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Answer 1

Benjamin Thompson 2022-8-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1780310-how-do-i-extract-fixed-width-columns-from-a-file-that-includes-empty-spaces#answer_1027575

Use the import data tool and configure the delimiter options to use space and treat multiple delimiters as one. You can generate sample code from that to reuse on other files.