Sorting Table Data by Groups of Rows
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Hello,
I have a very large data table consisting of timestamps and acceleration data. The data is grouped into packets where the timestamps are given once for every 10 acceleration values (timestamp followed by 9 NaN values and then another timestamp), and are not listed in any sort of order. I'm looking for a way to sort the data by timestamp, but also include the 9 rows with NaN following the timestamp, to get these groups of data sorted by timestamp in ascending order. Any help with how I could do this would be greatly appreciated.
{64,3889983,-304,-68,8172;64,NaN,-308,-64,8172;64,NaN,-284,-80,8168;64,NaN,-320,-24,8164;64,NaN,-292,-80,8176;64,NaN,-280,-84,8164;64,NaN,-276,-44,8184;64,NaN,-296,-80,8144;64,NaN,-296,-40,8160;64,NaN,-296,-76,8192;220,1840916,3052,2068,-7332;220,NaN,2984,1984,-7356;220,NaN,3044,2080,-7612;220,NaN,3116,1992,-7540;220,NaN,3060,1984,-7640;220,NaN,3120,1940,-7556;220,NaN,3004,1944,-7476;220,NaN,2892,1844,-7484;220,NaN,2892,1916,-7344;220,NaN,2844,1964,-7380}
1 Comment
Answers (2)
dpb
on 15 Aug 2019
Edited: dpb
on 23 Aug 2019
If the number of missing values is always 9, then extract the time column to a vector and
t=datatable(:,1); % retrieve the time data via whatever syntax need for how is stored
t=reshape(t,10,[]); % rearrange by set of 10 by column
for i=1:size(t,2) % over all columns
t(:,i)=t(1,i); % set to first value in column
end
datatable(:,1)=t(:); % replace values in original table via needed syntax
Now you can sort on the time column...
2 Comments
dpb
on 23 Aug 2019
Ooops...a typo. The RHS in the assignment is t(1,i), the first element of each column, not t(1,:).
Fixed up Answer...
Andrei Bobrov
on 21 Aug 2019
Let T - your table with size (176120x5) and T(:,1) - the timestamp column.
T{:,1} = fillmissing(T{:,1},'previous');
T_out = sortrows(T,1);
2 Comments
Andrei Bobrov
on 21 Aug 2019
i don't understand what you want, but maybe it:
A = [64,3889983,-304,-68,8172;64,NaN,-308,-64,8172;64,NaN,-284,-80,8168;64,NaN,-320,-24,8164;64,NaN,-292,-80,8176;64,NaN,-280,-84,8164;64,NaN,-276,-44,8184;64,NaN,-296,-80,8144;64,NaN,-296,-40,8160;64,NaN,-296,-76,8192;220,1840916,3052,2068,-7332;220,NaN,2984,1984,-7356;220,NaN,3044,2080,-7612;220,NaN,3116,1992,-7540;220,NaN,3060,1984,-7640;220,NaN,3120,1940,-7556;220,NaN,3004,1944,-7476;220,NaN,2892,1844,-7484;220,NaN,2892,1916,-7344;220,NaN,2844,1964,-7380];
T = array2table(A);
T.A6 = fillmissing(T.A2,'previous');
T = sortrows(T,'A6');
T_out = T(:,1:end-1);
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