Problem in special characters
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Dear all;
I have a ready code contain this command within a function
---------------------------------------------------
[pvdata,~]=xlsread([Newfolder, Mono70W999]);
when i lunch it an error appear ( tha path and the file names are correct)
Unrecognized function or variable 'Newfolder'.
Error in PVModuleCurveFitting/Open (line 85)
[pvdata,~]=xlsread([Newfolder, Mono70W999])
Error while evaluating UIControl Callback.
- I uhave problem understaning the use of square brackets in xlsread because i used to work with these syntax
num = xlsread(filename)
num = xlsread(filename,sheet)
num = xlsread(filename,xlRange)
num = xlsread(filename,sheet,xlRange)
num = xlsread(filename,sheet,xlRange,'basic')
[num,txt,raw] = xlsread(___)
- also i want to know the purpose of using ~ alone ?
Accepted Answer
1. The error, "Unrecognized function or variable 'Newfolder'." means that the variable 'Newfolder' is not defined in the function that's calling xlsread, at the time xlsread is called.
2. The square brackets construct a file name by horizontally concatenating the variables 'Newfolder' and 'Mono70W999'. Example:
Newfolder = 'C:\Data';
Mono70W999 = 'Project1.xlsx';
result = [Newfolder, Mono70W999]
Then that file name is passed to xlsread as the only input, so this is using the "num = xlsread(filename)" syntax.
Note that fullfile is better than square brackets for constructing file paths because it inserts directory separators between its arguments as needed. Example:
result = fullfile(Newfolder, Mono70W999)
[MATLAB Answers runs on a Linux platform,which uses slash ( / ) so that's why that's there. If you run it in Windows you'd get a backslash ( \ ) instead.]
3. The purpose of ~ is to indicate that the second output from xlsread is discarded. In this case, the ~ is unnecessary because the first output of xlsread is the same regardless of how many outputs are requested, so you'd get the same behavior with out = xlsread(filename) syntax.
Some other function besides xlsread might output different things depending on how many outputs are requested, in which case the [out1,~] = func(in) syntax might be necessary.
14 Comments
YASSER
on 27 Feb 2024
Voss
on 27 Feb 2024
Presuming that you want to read the file that was selected:
function Open(~,~)
[filename, pathname] = uigetfile('*.csv');
if isequal(filename,0) % Handling Cancel button pressed
return;
end
pvdata = xlsread(fullfile(pathname,filename));
Although readmatrix or readtable is recommended over xlsread.
Stephen23
on 27 Feb 2024
Please upload the CSV file Mono70W999.csv by clicking the paperclip button.
As Voss already recommended, you should use READTABLE or READMATRIX instead of XLSREAD.
Note that CSV files are not Excel files, they are text files. XLSREAD is the wrong tool.
Voss
on 27 Feb 2024
@YASSER: The file you have circled, Mono70W999.csv, appears to be located in 'C:\Users\HA\Desktop\PV Parameter estimation\CurveFittingTools', which makes its full path as follows:
'C:\Users\HA\Desktop\PV Parameter estimation\CurveFittingTools\Mono70W999.csv'
but you are trying to read
'C:\Users\HA\Desktop\PV Parameter estimation\CurveFittingTools\Newfolder\Mono70W999.csv'
Do you see the difference?
Also, why are you bothering to call uigetfile if you're not going to use its output?
I wrote:
pvdata = xlsread(fullfile(pathname,filename));
And you are doing:
pvdata = xlsread(fullfile(Newfolder,Mono70W999));
Do you want to read whatever file the user selected via uigetfile? If that's the case, use what I wrote and remove the variables Newfolder and Mono70W999.
Or do you want to always read the same Mono70W999.csv file, regardless of what file was selected with uigetfile? If that's the case, use what you wrote and remove the call to uigetfile.
YASSER
on 27 Feb 2024
Voss
on 27 Feb 2024
Please do as Stephen suggested and upload the file using the paperclip button.
YASSER
on 27 Feb 2024
Steven Lord
on 27 Feb 2024
Without seeing the actual file I think it's going to be impossible or nearly impossible to offer any suggestions for how to resolve the problem where you receive an [] as the output from xlsread. Just based on what we know already, I'm guessing the CSV file is empty. Seeing the actual file is the only way to confirm or refute my guess. So please attach the file to a comment as Stephen23 and Voss have requested using the button above the editor where you type your comment.
YASSER
on 28 Feb 2024
pathname = '.';
filename = 'Mono70W9999.csv';
readtable can read the file properly:
readtable(fullfile(pathname,filename),'NumHeaderLines',15,'VariableNamingRule','preserve','VariableNamesLine',15)
However, from your code I gather that you need the parameter values in the header as well, in which case it is convenient to use readmatrix instead:
pvdata = readmatrix(fullfile(pathname,filename))
disp(pvdata(4:14,2)) % parameters
disp(pvdata(16:end,:)) % data
plot(pvdata(16:end,1),pvdata(16:end,2))
xlsread generates an error with this file (it does not return an empty array):
xlsread(fullfile(pathname,filename))
YASSER
on 28 Feb 2024
Voss
on 28 Feb 2024
You're welcome!
More Answers (0)
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