texture.triangle.low.rv.high {aqp} | R Documentation |

This function accepts soil texture components (sand, silt, and clay percentages) and plots a soil texture triangle with a "representative value" (point) and low-high region (polygon) defined by quantiles. Marginal quantiles of sand, silt, and clay are used to define the boundary of a low-high region that encloses a severall likely soil texture classes based on the values in `ssc`

. The defualt settings place the RV symbol at the texture defined by marginal medians of sand, silt, and clay. The default low-high region is defined by the 5th and 95th marginal percentiles of sand, silt, and clay.

texture.triangle.low.rv.high(ssc, p=c(0.05, 0.5, 0.95), delta=1, pop.rv.col='red', range.col='RoyalBlue', range.alpha=75, sim=FALSE, sim.n=1000, sim.rv.col='yellow', sim.col=grey(0.95), sim.alpha=150, legend.cex=0.75, ...)

`ssc` |
a matrix-like object with columns: 'sand', 'silt', 'clay', values are percentages that should add to 100. |

`p` |
percentiles defining 'low', 'representative value', and 'high' |

`delta` |
step-size used to form low-high region |

`pop.rv.col` |
the symbol color used to denote the population representative value on the texture triangle |

`range.col` |
color of the polygon enclosing the low-high region |

`range.alpha` |
transparency of the low-high range polygon (0-255) |

`sim` |
optional simulation of low-rv-high values based on a composition drawn from normal distributions, this requires the 'compositions' package |

`sim.n` |
number of simulated sand, silt, and clay values |

`sim.rv.col` |
the symbol color used to denote the simulated representative value on the texture triangle |

`sim.col` |
color of the simulated low-high range polygon |

`sim.alpha` |
transparency of the simulated low-high range polygon (0-255) |

`legend.cex` |
scaling factor for legend |

`...` |
further arguments passed to |

Simulated sand, silt, and clay values are based on sampling from a normal distribution as performed by `rnorm.acomp`

in the 'comppositions' package. The mean vector of the sand, silt, and clay values, along with covariance matrix derived from `ssc`

are used to parametrize sampling.

A high-level plot as generated by `soil.texture`

.

Simulation of samd, silt, and clay values requires the 'compositions' package.

D.E. Beaudette

```
# sample data
data(loafercreek, package='soilDB')
# extract sand, silt, clay proportions
x <- na.omit(data.frame(sand=loafercreek$sand, silt=loafercreek$silt, clay=loafercreek$clay))
# test out the function
texture.triangle.low.rv.high(x, p=c(0.05, 0.5, 0.95))
```

```
texture.triangle.low.rv.high(x, p=c(0.25, 0.5, 0.75), range.col='darkgreen')
```

```
# simulate compositional data from source data
if(require(compositions)) {
# add simulated low-rv-high
texture.triangle.low.rv.high(x, p=c(0.05, 0.5, 0.95), sim=TRUE)
}
```

[Package *aqp* version 1.9.1 Index]