# computing montly averages when time series observations are irregural

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antonet on 28 Jul 2012
Dear all,
I have the following problem
Let
A ={
'02/11/08' [0.2150] [429.5674] [ 100] [2.2678e+04]
'30/11/08' [0.2117] [463.1360] [ 100] [2.4383e+04]
'28/12/08' [0.2209] [436.6316] [ 100] [2.3148e+04]
'25/01/09' [0.2212] [441.5430] [ 100] [2.2987e+04]
'22/02/09' [0.2201] [453.7015] [ 100] [2.3675e+04]
'22/03/09' [0.2185] [461.3925] [ 100] [2.3680e+04]
'19/04/09' [0.2104] [486.4095] [ 100] [2.5367e+04]
'17/05/09' [0.2162] [451.4833] [ 100] [2.3986e+04]
'14/06/09' [0.2158] [475.8620] [ 100] [2.4245e+04]
'12/07/09' [0.2211] [449.4574] [ 100] [2.2766e+04]
'09/08/09' [0.2221] [456.2507] [ 100] [2.2523e+04]
'06/09/09' [0.2175] [472.2659] [ 100] [2.3593e+04]
'04/10/09' [0.2182] [479.3408] [ 100] [2.4359e+04]
'01/11/09' [0.2286] [442.6719] [ 100] [2.1490e+04]
'29/11/09' [0.2211] [481.4548] [ 100] [2.4054e+04]
'27/12/09' [0.2259] [468.2757] [ 100] [2.3037e+04]
'31/01/10' [0.2300] [461.5581] [ 100] [2.2050e+04]
'28/02/10' [0.2259] [487.6257] [ 100] [2.3293e+04]
'28/03/10' [0.2200] [529.8777] [ 100] [2.5493e+04]
'25/04/10' [0.2315] [433.3039] [ 100] [2.0387e+04]
'23/05/10' [0.2274] [500.8603] [ 100] [2.4019e+04]
}
As you can see from the first column I have irregular time series observations. Each observation can represent a 4-week or a 5-week or a 6-week average. For example the observation [0.2117] which is the second value of the second column is the average of the values that have been recorded between ‘03/11/08' and '30/11/08' In order to be able to analyze econometrically these data and run my regressions I need to obtain regular time series observations. So I need to convert these values to monthly averages and have something like
Let A ={
'11/08' [mon. average] [mon. average] [mon. average]
'12/08' [mon. average] [mon. average] [mon. average]
'01/09' [mon. average] [mon. average] [mon. average]
'02/09' [mon. average] [mon. average] [mon. average]
'03/09' [mon. average] [mon. average] [mon. average]
'04/09' [mon. average] [mon. average] [mon. average]
'05/09' [mon. average] [mon. average] [mon. average]
'06/09' [mon. average] [mon. average] [mon. average]
'07/09' [mon. average] [mon. average] [mon. average]
'08/09' [mon. average] [mon. average] [mon. average]
'09/09' [mon. average] [mon. average] [mon. average]
'10/09' [mon. average] [mon. average] [mon. average]
'11/09' [mon. average] [mon. average] [mon. average]
'12/09' [mon. average] [mon. average] [mon. average]
}
Could interpolation be a solution to this problem? I would be grateful if you could provide some code.
cheers
antonet on 29 Jul 2012
Imager HELP!
thanks

per isakson on 28 Jul 2012
Edited: per isakson on 28 Jul 2012
Hint:
• vec = datevec( A{:,1}, 'dd/mm/yy' )
• out = accumarray( vec(:,2), A(something), [], @mean )
Better
vec = datevec( char(A{:,1}), 'dd/mm/yy' );
out = accumarray( vec(:,2:3), transpose([A{:,2}]), [], @mean );
This returns the means of the values of each month respectively. There is a value for each month. Is that what you want?
antonet on 28 Jul 2012
I will check the outcome and I will tell you. Thank you so much so the code!

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