Split array of strings and convert to numbers?

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schor
schor 2011-9-20
评论： Binod krushna 2023-7-27
Hello all, reading in a 2-columned spreadsheat file using xlsread gives me the following text-string (I couldn't manage this function to read in directly to numbers): '0,000' '1319,779017' '1,000' '1319,776931' '2,000' '1319,780805' '3,000' '1319,783785' ...and so on. Now, I want to convert column 1 into an array of numbers - let's say X, and column 2 into an array of numbers, let's say Y. Which function could I use for this? Many thanks in advance
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Jan
Jan 2011-9-20
What is column 1 and column 2? Is the comma the separator for the decimals? Does "text-string" mean, that the data are a cell string?

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回答（6 个）

Fangjun Jiang
Fangjun Jiang 2011-9-26
Use str2double() or str2num() instead. You are doing the opposite.
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Fangjun Jiang
Fangjun Jiang 2011-9-26
>> format long
>> str2double(A)
ans =
1.0e+009 *
1.319780805000000 1.319768288000000 1.319774249000000

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Tigersnooze
Tigersnooze 2011-9-20
What does your code look like? Normally when I use xlsread with a multi-column spreadsheet I get a multi-column array in return.
Something like:
[num, txt, dummy] = xlsread(filename, sheet)
Will return an m-by-n array in num, depending on the rows and columns in the sheet. I think you may also be running into problems because it looks like you have multiple values in each cell separated by commas, rather than two columns (if I'm reading that correctly--and assuming you're not using European-style numbers).
schor
schor 2011-9-26
Hi, I did exactly that, but it didn't work. Have I stored my data in an xls-format too new for Matlab (2007b)? Please find attached the xls file (which was automatically generated using LabVIEW). I get the following error message (running on Linux)
[num, txt, dummy] = xlsread(filename, sheet)
>> [num, txt, dummy] = xlsread('10mMHis_2mMTartaric_A_10_0.xls', 1)
Warning: XLSREAD has limited import functionality on non-Windows platforms
or in basic mode. Refer to HELP XLSREAD for more information.
> In xlsread at 201
??? Error using ==> biffread at 52
Unable to read XLS file
Ok now I've just realised that I can't attach anything here, maybe you guys could send me your email address? Many thanks!
schor
schor 2011-9-26
After some further examination, my question boils down to the point how an array of strings can be converted into an array of numbers:
A= '1319,780805'
'1319,768288'
'1319,774249'
...and so on, B=num2str(A) doesn't work, B=num2double(A) also doesn't work. Any ideas? Many thanks!
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Jan
Jan 2011-9-26
Is this a cell string or CHAR matrix? Is the comma the decimal separator or a kind of column separator?

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Jan
Jan 2011-9-26
If A is a cell string and the comma is the decimal point:
A = {'1319,780805', '1319,768288', '1319,774249'};
A = strrep(A, ',', '.');
S = sprintf('%s*', A{:});
Num = sscanf(S, '%g*');
This is very fast even for large arrays.
schor
schor 2011-9-27
Thank you very much, that did the trick!

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