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Defining export files

Index

The Save Statement

Allows to save data in a file. The type of file can be “shp”, “text” or “csv”. The save statement can be use in an init block, a reflex, an action or in a user command. Do not use it in experiments.

Facets

  • to (string): an expression that evaluates to an string, the path to the file
  • data (any type), (omissible) : any expression, that will be saved in the file
  • crs (any type): the name of the projectsion, e.g. crs:”EPSG:4326” or its EPSG id, e.g. crs:4326. Here a list of the CRS codes (and EPSG id): http://spatialreference.org
  • rewrite (boolean): an expression that evaluates to a boolean, specifying whether the save will ecrase the file or append data at the end of it
  • type (an identifier): an expression that evaluates to an string, the type of the output file (it can be only “shp”, “text” or “csv”)
  • with (map):

Usages

  • Its simple syntax is:
save data to: output_file type: a_type_file;
  • To save data in a text file:
save (string(cycle) + "->"  + name + ":" + location) to: "save_data.txt" type: "text";
  • To save the values of some attributes of the current agent in csv file:
save [name, location, host] to: "save_data.csv" type: "csv";
  • To save the geometries of all the agents of a species into a shapefile (with optional attributes):
save species_of(self) to: "save_shapefile.shp" type: "shp" with: [name::"nameAgent", location::"locationAgent"] crs: "EPSG:4326";

Export files in experiment

Displays are not the only output you can manage in GAMA. Saving data to a file during an experiment can also be achieved in several ways, depending on the needs of the modeler. One way is provided by the save statement, which can be used everywhere in a model or a species. The other way, described here, is to include an output_file statement in the output section.

output_file name:"file_name" type:file_type data:data_to_write; 

with:

file_type: text, csv or xml file_name: string data_to_write: string

Example:

file name: "results" type: text data: time + "; " + nb_preys + ";" + nb_predators refresh:every(2);  

Each time step (or according to the frequency defined in the refresh facet of the file output), a new line will be added at the end of the file. If rewrite: false is defined in its facets, a new file will be created for each simulation (identified by a timestamp in its name).

Optionally, a footer and a header can also be described with the corresponding facets (of type string).

Autosave

Image files can be exported also through the autosave facet of the display, as explained in this previous part. //: # (endConcept|export_files)