# MATLAB: Help correcting a messy time series data

missing datamixed datatime series

Hi,
I have multiple files of "daily" minimum temperature. The time series is non-continuos. Files start and end in different dates, some days in the middle are missing (the rows are missing), and some days have more than one measurement.
This is an example of what I have:
1999 01 01   5.21999 01 02   4.31999 01 02   5.01999 01 02   4.11999 01 03   3.81999 01 05   3.2...
So day 02-jan has 3 different meassurements and day 04-jan is missing. Say that I need all the files to begin at 31-dec-1998 and end at 07-jan-1999, my files should end up looking like this:
1999 12 31   6.61999 01 01   5.21999 01 02   4.11999 01 03   3.81999 01 04   NaN1999 01 05   3.21999 01 06   NaN1999 01 07   NaN
So far I managed, using this thread , to fill the missing dates with NaNs.
I still need to:
1) take the minimum value of the days with more than one measurement. I have absolutely no idea how to do this…
2) complete the period with NaN or crop the data between the starting and the ending date that I need. So far I managed with a long and messy script to crop and/or add the missing data at the end. But I couldn't make that work for the beggining, and I'm sure there must be an easier, more effective way of doing so.
• YMD_data = YourData(:,1:3);temperature_data = YourData(:,4);  %must be column vectorfirst_wanted = datenum('31-dec-1998');last_wanted = datenum('07-jan-1999');dayspan = last_wanted - first_wanted + 1;dnum = datenum(YMD_data);in_range = first_wanted <= dnum & dnum <= last_wanted;useful_dnum = dnum(in_range);useful_temperature = temperature_data(in_range);relday = useful_dnum - min(first_wanted) + 1;  %so first day is 1, next is 2, etcmintemp = accumarray(relday, useful_temperature, [dayspan, 1], @min, NaN);wanted_dates_vec = datevec(first_wanted : last_wanted);results = wanted_dates_vec(:,1:3, mintemp);