extract daily data
in [Matlab]
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From: Benedikt Heudorfer on 16 Jun 2010 10:03 dpb <none(a)non.net> wrote in message <hv8n31$vkn$1(a)news.eternal-september.org>... > TideMan wrote: > > On Jun 16, 2:50 am, "Benedikt Heudorfer" <rawk...(a)web.de> wrote: > >> "Benedikt Heudorfer" <rawk...(a)web.de> wrote in message <hv7vns$m2...(a)fred.mathworks.com>... > >>> "Benedikt Heudorfer" <rawk...(a)web.de> wrote in message <hv7qh3$j3...(a)fred.mathworks.com>... > >>>> Hey there! > >>>> I have measured data over 10 years saved in a txt file. The data is about flow rate. Each data entry is connected to a date (in dd.mm.yyyy). data is in column 4, date is in column 2 of the file. What I need to do is to sum up the data over every day to get a daily value. > >>>> So I have to extract daily data. Problem is that moment of measuring as well the interval (e.g. 10.30 - 11.00 - 11.30 - 12.44 - 13.44 ...) changes some times (due to measurement errors). So the time as well as the number of data per day changes permanently. So I need Matlab to identify the data as appendant to each other according to the date (!) and then to sum it up directly so i can save it on. Can you help? > >>> Ok let me rephrase this. For every day in column 2, the accordant data in column 4 should be summed up. > >>> For this, I think need a code to automatically identify the days out of the time-column 2... or something like that. > >> Any hint would be helpful. E.g. which commands i couldtry. I'm really stuck here. > >> Thanks, Ben > > > > 1. Read the data into Matlab using textscan > > 2. Convert the dates to Matlab days using datenum > > 3. Use diff on the times to figure out the finish index of each day. > > Adding 1 to this will give the start index of the next day. > > 4. Loop through the days, averaging between each start and finish > > address. > > Alternatively, since days are whole integers in datenum form, a unique() > operation on floor() would provide the individual days and an optional > index array for each set belong to each day that could be used as the > index for the sum() selection. > > -- second was helpful! thanks a lot |