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How to convert quarterly data into monthly and merge together

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Dear all, I have a quarterly data and some monthly data. I want to convert the quarterly into a monthly format where the new data will only have the Q1(MARCH) Q2(JUNE) Q3(SEPTEMBER) AND Q4( DECEMBER) will only have values while the remaining months will be filled with NA.
For example,
Quarterly
2000q1. 12
2000q2. 14
2000q3. 18
2000q4. 22
New data Monthly 2000m1 Na 2000m2. Na 2000m3. 12 2000m4. Na 2000m5. Na 2000m6. 14 2000m7. Na 2000m8. Na 20000m9 18 2000m10. Na 2000m11. Na 2000m12. 22 After which I will merge the data together and the end result will have quarterly data repeated for the monthly NA.

Risposte (1)

dpb
dpb il 15 Ott 2023
Modificato: dpb il 15 Ott 2023
Your described process, while it would work, is going "'round Robin Hood's barn" to get there.
Use a timetable and retime and it comes out automagically...
ttQ=timetable(datetime(2000,[3:3:12].',1),[12; 14;18;22])
ttQ = 4×1 timetable
Time Var1 ___________ ____ 01-Mar-2000 12 01-Jun-2000 14 01-Sep-2000 18 01-Dec-2000 22
ttQ=retime(ttQ,'monthly','previous')
ttQ = 10×1 timetable
Time Var1 ___________ ____ 01-Mar-2000 12 01-Apr-2000 12 01-May-2000 12 01-Jun-2000 14 01-Jul-2000 14 01-Aug-2000 14 01-Sep-2000 18 01-Oct-2000 18 01-Nov-2000 18 01-Dec-2000 22
  8 Commenti
dpb
dpb il 16 Ott 2023
You'll have to have exactly as many values of GDP to assign as the number of elements in the indexing vector you create. The index I used of
3:3:12
ans = 1×4
3 6 9 12
has only four values in it to match the values in the original question; didn't have any more at the time.
Try
Date=[datetime(2005,1,1):calmonths(1):datetime(2022,3,31)].';
TtQ=timetable(Date,nan(size(Date)),'VariableNames',{'GDP'});
TtQ.GDP(3:3:end)=GDP.GDP; % use whatever is the column variable in the table
It may be off by one; just fix up the index array to match whatever the length is. Or, alternatively, you can create a logical indexing vector by matching the timestamp in the GDP timeseries as
TtQ.GDP(TtQ.Date==GDP.Time)=GDP.GDP; % use what are the column variables in the table
I can't see your original data so am having to guess about what the timeseries itself is named as well as the timestamp and data column names; use whatever they really are. There's no reason to need array2table, just reference the variable out of the timetable/timeseries.
Hamid Muili
Hamid Muili il 30 Apr 2024 alle 16:01
Thanks a lot, attached is the quarterly data used. I was able to generate the Ttq, however, I got an error when I used Ttq.GDP(3:3:end)=gdp.GDP It showed " unable to perform assignment because the left and right sides have a different number of elements ".

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