This code creates a pl/R function for creating texture triangles directly from a PostgreSQL database.This example is composed by three pl/R files (_plr_clasif_textural_usage.sql, _plr_clasif_textural.sql and _plr_clasif_textural.R). This code is quite old and it would look better using the "The Soil Texture Wizard" package. Want more info? Visit…

_plr_clasif_textural.R

# Cargamos las librerias necesarias
library(Cairo)
library(plotrix)
# Definimos la funcion
clasif.textural = function (soiltexture = NULL, at = seq(0.1, 0.9, by = 0.1),
axis.labels = c("% arena (entre 0,05 y 2 mm)", "% limo (entre 0,05 y 0,002 mm)", "% arcilla (menor de 0,002  mm)"),
tick.labels = list(l = seq(10, 90, by = 10), r = seq(10,
90, by = 10), b = seq(10, 90, by = 10)), show.names = TRUE,
show.lines = TRUE, col.names = "black", bg.names = par("bg"),
show.grid = TRUE, col.axis = "black", col.lines = "black",
col.grid = "gray", lty.grid = 3, show.legend = FALSE, label.points = FALSE,
point.labels = '', col.symbols = "blue", pch = par("pch"),
...)
{
par(xpd = TRUE)
plot(0.5, type = "n", axes = FALSE, xlim = c(0, 1), ylim = c(0,
1), main = NA, xlab = NA, ylab = NA)
triax.frame(at = at, axis.labels = axis.labels,
tick.labels = tick.labels, col.axis = col.axis, show.grid = show.grid,
col.grid = col.grid, lty.grid = lty.grid)
arrows(0.12, 0.41, 0.22, 0.57, length = 0.15)
arrows(0.78, 0.57, 0.88, 0.41, length = 0.15)
arrows(0.6, -0.1, 0.38, -0.1, length = 0.15)
if (show.lines) {
triax.segments <- function(h1, h3, t1, t3, col) {
segments(1 - h1 - h3/2, h3 * sin(pi/3), 1 - t1 -
t3/2, t3 * sin(pi/3), col = col)
}
h1 <- c(85, 70, 80, 52, 52, 50, 20, 8, 52, 45, 45, 65,
45, 20, 20)/100
h3 <- c(0, 0, 20, 20, 7, 0, 0, 12, 20, 27, 27, 35, 40,
27, 40)/100
t1 <- c(90, 85, 52, 52, 43, 23, 8, 0, 45, 0, 45, 45,
0, 20, 0)/100
t3 <- c(10, 15, 20, 7, 7, 27, 12, 12, 27, 27, 55, 35,
40, 40, 60)/100
triax.segments(h1, h3, t1, t3, col.lines)
}
if (show.names) {
xpos <- c(0.5, 0.7, 0.7, 0.73, 0.73, 0.5, 0.275, 0.275,
0.27, 0.27, 0.25, 0.135, 0.18, 0.07, 0.49, 0.72,
0.9)
ypos <- c(0.66, 0.49, 0.44, 0.36, 0.32, 0.35, 0.43, 0.39,
0.3, 0.26, 0.13, 0.072, 0.032, 0.024, 0.18, 0.15,
0.06) * sin(pi/3)
snames <- c("arcillosa", "arcillosa", "limosa", "franco arcillosa", "limosa",
"franco arcillosa", "arcillosa", "arenosa", "franco arcillosa", "arenosa",
"franco arenosa", "arenosa", "franca", "arenosa", "franca", "franco limosa",
"limosa")
boxed.labels(xpos, ypos, snames, border = FALSE, col = col.names,
cex=0.8, xpad = 0.5)
}
par(xpd = FALSE)
if (is.null(soiltexture))
return(NULL)
soilpoints <- triax.points(soiltexture, show.legend = show.legend,
label.points = label.points, point.labels = point.labels,
col.symbols = col.symbols, pch = pch, ...)
invisible(soilpoints)
}
# Definimos la imagen
CairoPNG("…/images/clasificacion_textural.png", width=500, height=560)
# Construimos las consultas
select = 'select '
arena = paste(arg1, ',', sep=' ');
limo = paste(arg2, ',', sep=' ');
arcilla = paste(arg3, ' ');
from = ' from '
tabla = arg4
selection = paste(select, arena, limo, arcilla, from, tabla, sep='');
selectgids = paste('select gid', from, tabla, sep='');
# Ejecutamos las consultas
texturas <- pg.spi.exec(selection)
gids<- pg.spi.exec(selectgids)
# Ejecutamos la funcion creada mas arriba
soiltex.return<-clasif.textural(texturas,
pch=arg5, point.labels = gids[,], label.points=arg6)
dev.off()
# Damos permisos de lectura
system('chmod go+r …/images/clasificacion_textural.png');
# Una comprobacion para asegurarnos de que se ha creado la grafica, pero no afecta para nada.
if (file.exists('…/images/clasificacion_textural.png')) {
print ('Grafico realizado. Se llama …/images/clasificacion_textural.png')};