MeteoIODoc  MeteoIODoc-2.7.0
Quick overview

This library contains various classes that have been designed to deal with various sets of problems. This page shows the different sets of problems and what kind of functionnality the library offers to tackle them.

Class structure

structure.png
simplified class structure

Data reading

The class IOHandler provides the meteorological data from the sources selected by the user in its configuration file. This class inherits from IOInterface and is implemented through plugins that are responsible for implementing a given data access (see Plugins developer's guide for more information). It therefore proposes a uniform, standardized access to the data that can be meteorological data, gridded data (including Digital Elevation Model (DEM) data or variations like for landuse codes) and tables of coordinates (for special processing at users selected locations). A buffered version of this class exists: BufferedIOHandler that should be prefered. The description of the plugins and their usage can be found in Available plugins. This class also transparently calls the filtering class, FilterAlgorithms in order to filter the data according to the configuration of the user.

Meteorological data

The data structures designed for storing meteorological data have been split into two classes: MeteoData and StationData.

MeteoData

The class MeteoData stores the measurement data coming from some idealized station. It contains the widest set of meteorological measurements. It can be compared, assigned and set (either using a constructor or by calling a set method). Its meteorological parameters can be directly accessed or using a param() method that takes a enum in order to be able to cycle through the parameters.

StationData

The class StationData contains the metadata of a weather station, that is mostly its location. It supports the comparison operators.

Getting the data

The getMeteoData method defined in the IOHandler class provides a vector of MeteoData and StationData for the requested time step. More details are given in Data reading .

Arrays related functionnalities

Arrays

The classes Array, Array2D and Array3D are designed for the storage and handling of 1D, 2D, 3D arrays in memory. These classes provide access to a given element (read/write), sizing or resizing of an existing array as well as clearing an array. They also provide the minimum and the maximum of the values that are stored in the array. Finally, a subset of an array can be extracted.

Grids

Built on top of the arrays, defined as classes Grid2DObject and Grid3DObject, the grids add the geolocalization. This means that the coordinates of the lower-left corner of the array are stored as well as the cellsize. They can be built manually, or by providing an array. A subset constructor is available, allowing to extract a subset of the grid. It is also possible to get the lat/long (in WGS84) coordinates matching an (i,j) coordinate in the grid. Finally, It is possible to test for geolocalization equality (ie: do two grids have the same geolocalization).

Digital Elevation Models

The last layer for gridded data is class DEMObject. Various parameters that are specific to Digital Elevation Models (DEM) are added: for each grid point, the slope, the azimuth, the curvature as well as the normal vector are defined (an optional parameter can be used to select the algorithm to be used). The minimums and maximums (over the grid) for each of these parameters are available. A subset of the DEM can be extracted using the subset constructor.

Geographic projections

The class Coords is dedicated to geographic projections. It can use projections provided by libproj4 or internal implementations provided by the CoordsAlgorithms static class alongside a set of helper algorithms (such as grid rotation, datum conversion, etc).

Coordinate conversion

The class Coords takes one or two arguments describing the coordinate system of the input data and then converts back and forth with lat/long WGS84. It can be used to construct a local coordinate system, that is to say a metric grid whose origin is chosen by the user (through the lat/long parameters provided to the constructor). This is useful when working with multiple gridded coordinate system in order to get a common system that would still allow easy distances calculations. See the supported projections.

Distances

A few method used internally to work with custom, local grids are exposed to the user in order to easily compute distances beetwen points (using their lat/long). The algorithms can optionnaly be chosen (otherwise a default choice is used).

Interpolations

Spatial interpolations

The class Meteo2DInterpolator receives a Digital Elevation Model (DEM) in its constructor as well as two vectors, one of MeteoData the other one of StationData. Then it allows filling 2D grid (as Grid2DObject) with spatially interpolated meteorological parameters.

1D interpolations

The ResamplingAlgorithms class uses the Interpol1D class to perform temporal interpolations (for resampling).

Configuration files handling

In order to offer a consistent interface to the user as well as make it easy to read configuration parameters, the class Config is exposed. Once constructed with a configuration file name, each key's parameter can be retrieved with a call to the templatized getValue() method.

Dates handling

Dates should be constructed as a Date object. Then, it is easy to built a new date from a julian date, from an ISO formatted date string, from a date split in fields or from a UNIX date (number of seconds since epoch). Then the various representation of the date can be retrieved, the date arithmetics can be done (for example, get the date that is 1 year, 3 months, 15 hours after 2008-12-01T11:54:00) as well as comparisons. The date printing can be controlled by keywords.

Exceptions

A few customized exceptions have been defined in IOException : these exceptions have to do with I/O, parameter parsing, argument validity, etc and consistently print usefull debuging information when thrown.

Miscellaneous

The IOUtils class is a static class that contains a few helper functions, in order to deal with things as diverse as units conversions, checking for file presence, equality within a given epsilon, string parsing.