Geoscience Reference
In-Depth Information
(a)
(b)
FIGURE 14.4
(a) Choropleth and (b) pycnophylactic interpolation maps of the leukaemia rate 1978-1982,
New York state 8 county data set (note that figure class intervals are not aligned with each other).
R interactive session
System('g.region −p')
System('psql midwest')
.Call('gmeta')
GRASS environment and location
System shell and environment (csh, ksh, bash)
Underlying operating system
FIGURE 14.5
Design of software layering in the GRASS 5 interface to
R
, using compiled C code.
R error handler and to remove all calls to exit in GRASS C code. Merging in revisions from the
GRASS code repository was demanding, but the interface served for 5 years, supporting among
others Grohmann (2004) in work on morphometric analysis and Garzón et al. (2006) on predict-
ing habitat suitability.
Figure 14.6, showing the relative positions of software components, has two readings: the contin-
uous line bounded box represents a setting similar to that of the
GRASS
package, with
R
facing the
users. The second reading is the larger dashed box, where
R
is a computational software component
in a larger system, with a GIS or other (web) application facing the users, probably through a GUI.
The application then uses
R
, thought of as running within a GIS session and location, to handle data
from storage for visualisation and/or storage.
GRASS 6 was released in March 2005 and has now reached 6.4.3 (GRASS Development Team
2012). Bivand et al. (2008, pp. 99-106) and Neteler and Mitasova (2008, pp. 353-364) describe
the use of the reimplemented interface package
spgrass6
, which works with GRASS 6 and the
development version GRASS 7. The interface was released from a Sourceforge project at the same
time as GRASS 6 and was accepted on CRAN in August 2006, to be ready for a workshop at
