interp_param: Interpolate weights for a vector of values

In asgr/ProSpect: Professional Spectral Analysis Package

Interpolate weights for a vector of values

Description

Utility functions to interpolate the lineat of log spaced weights for a vector of values. This can be used to create interpolations for x versus y type data, but it is more useful when the property to be weighted is non-trivial, e.g. you have spectra on a grid of metallicities and you want to interpolate between values. interp_quick is faster, but can only be used for single value lookups, has less flesibility, and returns less information.

Usage

interp_param(x, params, log = FALSE, method = "linear")
interp_quick(x, params, log = FALSE)

Arguments

x	Numeric vector; the value/s to use for the interpolation. For interp_quick this can only be a scalar.
params	Numeric vector; the values to be interpolated.
log	Logical scalar; should the interpolation be done in linear space (log=FALSE, the default), or log space (log=TRUE).
method	One of “constant", “linear", “nearest", “spline", or “cubic"; default is “linear". This is passed to interp1.

Details

This routine is used to calculate appropriate weights for a number of interpolations within ProSpect, where outputs are often generated for fixed grids of parameters (e.g. metallicity, AGN fraction and radiation field).

Value

x param_lo param_hi ID_lo weight_lo ID_hi weight_hi flag A data.frame with the same number of rows as the length of x, with columns:

x	The value/s uses for the interpolation (might be different to the input x if this went beyond the limits of params)
param_lo	The nearest value of params lower than x
param_hi	The nearest value of params higher than x
ID_lo	The location ID of the nearest value of params lower than x
ID_hi	The location ID of the nearest value of params higher than x
ID_mode	The ID with the most weight between ID_lo and ID_hi
wt_lo	The interpolation weight to be applied to the nearest value of params lower than x
wt_hi	The interpolation weight to be applied to the nearest value of params higher than x
flag	Interpolation flag: 0 means the input x is at an exact value of params, in which case ID_lo=ID_hi, weight_lo=1 and weight_hi=0; 1 means x is less than the minimum of params, so forced to this value; 2 means x is between two values in params, so interpolation behaves in a standard sense; 3 means x is more than the maximum of params, so forced to this value

Note

In the output, flag=2 is the "normal" flag in the sense the interpolation has not gone beyond the limits of params and is not trivial (as exact value of params).

Author(s)

Aaron Robotham

See Also

Dale_interp

Examples

interp_param(c(0.1,3.3,5.8,8,11.2),1:10)

asgr/ProSpect documentation built on Feb. 21, 2025, 1:43 a.m.