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Hi

I have a table with four columns and roughly 45,000 rows (example below). The first column is the name of statistical test (of which there are several hundred different tests). For every statistical test the values in the 4th column are duplicated (at .25 and 0.5). Can anyone advise how I delete the first of these rows (the first one of the .25 and the first one of the 0.5 rows) for every statistical test?

'Perm t-test equal [250ms,500ms 92, 108]: Avg: 11_right FCL' -1.349 0.185 0.492

'Perm t-test equal [250ms,500ms 92, 108]: Avg: 11_right FCL' -1.457 0.155 0.496

'Perm t-test equal [250ms,500ms 92, 108]: Avg: 11_right FCL' -1.544 0.134 0.500

'Perm t-test equal [500ms,900ms 92, 108]: Avg: 11_right FCL' -1.544 0.129 0.500

'Perm t-test equal [500ms,900ms 92, 108]: Avg: 11_right FCL' -1.615 0.112 0.503

'Perm t-test equal [500ms,900ms 92, 108]: Avg: 11_right FCL' -1.665 0.100 0.507

dpb
on 20 Jan 2021

I don't see the duplication in the sample dataset? (I'm presuming the 0.25 and 0.5 are confidence limits of the test and not values of the statistic as Adam presumed below).

To my eyes anyways, the above data are all for the same test for the first three and then the second set of three; but the fourth column data values are unique other than by happenstance it appears that the last @250ms is same in second and fourth columns as the first @500ms.

Not at all clear what is the result wanted from this dataset, to me, anyways...

Adam Danz
on 20 Jan 2021

Edited: Adam Danz
on 20 Jan 2021

Follow the demo.

- T is a table
- T.Test contains the test names which can be strings, character vectors, categoricals, or numeric.
- T.col4 is the name of column 4.

The demo removes the first line where column 4 equals 0.25 or 0.50 for each test. The tests do not have to be in order.

% Create table

rng('default') % for reproducibility

T = table(repelem({'A';'B';'C'},5,1),rand(15,1), rand(15,1), repmat([0;.25;.25;.5;.5],3,1),...

'VariableNames',{'Test','col2','col3','col4'});

T.col4([7,14]) = .33;

disp(T)

% For each testtype, identify the first row where col4 is .25 and .50

[testID, testNames] = findgroups(T.Test);

rowNum1 = arrayfun(@(i) {find(testID==i & T.col4==0.25, 2)}, unique(testID));

rowNum2 = arrayfun(@(i) {find(testID==i & T.col4==0.50, 2)}, unique(testID));

rowNums = cell2mat(cellfun(@(c){padarray(c,[2-numel(c),0],NaN,'post')},[rowNum1', rowNum2']));

rmRows = rowNums(2, ~isnan(rowNums(2,:)));

% remove rows from table

T(rmRows, : ) = []

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