# Aggregating Data Files

Autoplot allows data from multiple files to be combined into one dataset through an aggregation specification. Data must be time-ordered, and each file must have time as the first data dimension.

For example, `vap:http://cdaweb.gsfc.nasa.gov/istp_public/data/ace/swe/$Y/ac_k0_swe_$Y$m$d_v...cdf?Np&timerange=2009+Apr"` loads each if the files covering the interval April 2009 and combines them.

The text field in this GUI is for specifying the time range. Most human-readable formats should be parsed correctly, but here are some examples:

- 2009-Apr: The month of April 2009.
- 2009-4-11: April 11, 2009.
- 2009: The entire year of 2009.
- 2009-095: three-digit day of year (April 5, 2009)
- 2009-4-5 to 2009-4-11: the time range covering the interval. Note 2009-4-11 is excluded from the interval, "through" includes it.

This component will attempt to show what data is available for the given specification. The droplist components can be used to select a year, month or date, and then "Copy" will copy the selection to the Time Range text field. Note the keywords "to" and "through" allow for arbitrary ranges.

Here field codes:

- $Y four-digit year
- $y two-digit year
- $j three-digit day of year
- $m two-digit month
- $d two-digit day of month
- $H two-digit hour
- $M two-digit minute
- $S two-digit second
- $v version number, numerical sort $(v,alpha) $(v,sep) for "x.y.z"
- $(milli) three digit milliseconds
- $(micro) three digit microseconds

this page in the wiki