Can I merge two matrices of different length with respect to a date column contained in both?

2 次查看（过去 30 天）
Benedict Keim
Benedict Keim 2016-12-13
回答： Peter Perkins 2016-12-19
I have two matrices each containing date numbers in the first and observations in the second column. I would like to merge them so that my new matrix only contains the dates present in both matrices and the matching observations - it should be a three column matrix [dates obsMatrix1 obsMatrix2]

请先登录，再回答此问题。

采纳的回答

Jos (10584)
Jos (10584) 2016-12-13
Take a look at INTERSECT. Something along these lines could work:
[~,i,j] = intersect(A(:,1),B(:,1))
C = [A(i,:) B(j,2)]

更多回答（3 个）

Guillaume
Guillaume 2016-12-13
编辑：Guillaume 2016-12-13
It's trivial to do using intersect:
tstart = datenum(now);
t1 = [tstart + (0:19); 1:20] .' %demo matrix
t2 = [tstart + (1:2:21); 101:2:121] .' %demo matrix
[commontime, t1rows, t2rows] = intersect(t1(:, 1), t2(:, 1));
tcommon = [commontime, t1(t1rows, 2), t2(t2rows, 2)]
Or using the synchronize method of new timetable class (which gives a lot more flexibility):
tt1 = timetable(datetime(t1(:, 1), 'ConvertFrom', 'datenum'), t1(:, 2));
tt2 = timetable(datetime(t2(:, 1), 'ConvertFrom', 'datenum'), t2(:, 2));
tcommon = synchronize(tt1, tt2, 'intersection')
I recommend you move to using timetables.
Jan
Jan 2016-12-13
[Lia, Locb] = ismember(A, B);
C = cat(2, A(Lia, :), B(LocB, 2));
Peter Perkins
Peter Perkins 2016-12-19
Benedict, you might find that using tables and their various join methods makes what you're doing very straight-forward. The following assumes you have at least R2014b, with datetime, but that's not crucial:
>> Date = datetime(2016,12,[1 2 3 5]');
>> Value = randn(4,1);
>> T1 = table(Date,Value)
T1 =
Date Value
___________ _______
01-Dec-2016 0.53767
02-Dec-2016 1.8339
03-Dec-2016 -2.2588
05-Dec-2016 0.86217
>> Date = datetime(2016,12,[1 3 4 5]');
>> Value = randn(4,1);
>> T2 = table(Date,Value)
T2 =
Date Value
___________ ________
01-Dec-2016 0.31877
03-Dec-2016 -1.3077
04-Dec-2016 -0.43359
05-Dec-2016 0.34262
>> T12 = innerjoin(T1,T2,'Key','Date')
T12 =
Date Value_T1 Value_T2
___________ ________ ________
01-Dec-2016 0.53767 0.31877
03-Dec-2016 -2.2588 -1.3077
05-Dec-2016 0.86217 0.34262
>> T12 = outerjoin(T1,T2,'Key','Date')
T12 =
Date_T1 Value_T1 Date_T2 Value_T2
___________ ________ ___________ ________
01-Dec-2016 0.53767 01-Dec-2016 0.31877
02-Dec-2016 1.8339 NaT NaN
03-Dec-2016 -2.2588 03-Dec-2016 -1.3077
NaT NaN 04-Dec-2016 -0.43359
05-Dec-2016 0.86217 05-Dec-2016 0.34262
You can do all that by hand using intersect and so on, but it's all already there in inner/outerjoin. And as Guillaume says, if you have R2016b, you should look at timetables.

类别

在 Help Center 和 File Exchange 中查找有关 Time Series Objects 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by