- X data are floating point and the values are close to, but not precisely 1 so the test for equality fails. This probably isn't the case here, but is common enough as to mention it and it is at least possible from the information we have available to us
- There are other data in X that are NaN besides those that your filter has cleaned up so the result of the calculation is still NaN (which, while you don't say what the result returned was, the crystal ball is back from the shop (again!) and it says that's the symptom.
How do I delete cells in a column based on information from another column?
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Hi,
I am working on data that I have extracted from an excel sheet. I have extracted the three columns that are necessary but need to do further work until I can use the data. Column three tells me if the data is valid hence I need to write the code that if any cells in column three equals 1 the correspoding cells in column 1 and 2 are equal to nan or 0. I then need that if column 1 equals to zero the corresponding cells in cloumn 2 equals to nan or 0. I then need to sum column 1 and average column 2. Below is the code I have tried. It runs but the output it gives is the sum and average of the columns before the if statements.
X = xlsread('filename.csv');
x = [X(:,2) X(:,3) X(:,9)];
if (x(:,3) == 1), x(:,1)= 0;
end
if (x(:,3) == 1), x(:,2)= 0;
end
if (x(:,1) == 0), x(:,2)= 0;
end
sum(x(:,1))
mean(x(:,2))
3 个评论
dpb
2020-2-28
编辑:dpb
2020-2-28
I guess will have to send the crystal ball back out for repair...it seems to still be murky! :)
That said, I'm pretty confident that you've not uncovered a bug in the ML sum() function so I'll assert the answer in ML is 5 and 9E5.
We'd have to see the input file to see what it is precisely that caused the differences.
I'll try the crystal ball one more time before declaring it broken (yet again)--
Does the input file have a header row, perchance? The difference between 3 and 5 is 2 and two headerlines would be a very common occurrence in a spreadsheet. There being some other value in one of those two lines that is also numeric in the second column is also certainly quite possible.
采纳的回答
Guillaume
2020-3-2
Considering the format of your spreadsheet you would be better off importing the data as a table. If I understood correctly what you're trying to achieve, this would do it:
testresults = readtable('WM TEST.xlsx'); %import data as table. Matlab automatically detect the column headers and use that to name the table variables
isgoodtest = testresults.Correct & ~testresults.FailedTrial; %a good test is one with correct result and not failed
meangoodsaccade = mean(testresults.SaccadeTimeToChooseCurtain(isgoodtest); %mean of saccade time for these tests that are correct and not failed
countgoodtest = nnz(isgoodtest);
As you can see, there is no need to remove anything, so if you want to compute some other statistics the source data is still there, and it's much easier to understand what the code is doing and the code is simpler as well. Good variable names help with code clarity.
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Pujitha Narra
2020-3-2
编辑:Pujitha Narra
2020-3-2
Hi,
According to the code above, the condition for the ‘if’ would return a column vector, but the ‘if’ requires the entire vetor to contain logical true values. This is causing the unexpected results.
Instead use the following code instead of the ‘if’ statements:
x(find(x(:,3)==1),1) =0;
x(find(x(:,3)==1),2) =0;
x(find(x(:,3)==0),2) =0;
5 个评论
Pujitha Narra
2020-3-2
I agree with Guillaume and Stephen. 'if' tries to check if the entire vector has logical true values in this case, not just the first element (as wrongly mentioned previously)
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