`R/compare_groups.R`

`compare_groups.Rd`

This function takes in an object of class `simmr_output`

and creates
probabilistic comparisons for a given source and a set of at least two
groups.

```
compare_groups(
simmr_out,
source_name = simmr_out$input$source_names[1],
groups = 1:2,
plot = TRUE
)
```

- simmr_out
An object of class

`simmr_output`

created from`simmr_mcmc`

or`simmr_ffvb`

.- source_name
The name of a source. This should match the names exactly given to

`simmr_load`

.- groups
The integer values of the group numbers to be compared. At least two groups must be specified.

- plot
A logical value specifying whether plots should be produced or not.

If there are two groups, a vector containing the differences between the two groups proportions for that source. If there are multiple groups, a list containing the following fields:

- Ordering
The different possible orderings of the dietary proportions across groups

- out_all
The dietary proportions for this source across the groups specified as columns in a matrix

When two groups are specified, the function produces a direct calculation of the probability that one group is bigger than the other. When more than two groups are given, the function produces a set of most likely probabilistic orderings for each combination of groups. The function produces boxplots by default and also allows for the storage of the output for further analysis if required.

See `simmr_mcmc`

for complete examples.

```
if (FALSE) {
data(geese_data)
simmr_in <- with(
geese_data,
simmr_load(
mixtures = mixtures,
source_names = source_names,
source_means = source_means,
source_sds = source_sds,
correction_means = correction_means,
correction_sds = correction_sds,
concentration_means = concentration_means,
group = groups
)
)
# Print
simmr_in
# Plot
plot(simmr_in,
group = 1:8, xlab = expression(paste(delta^13, "C (per mille)", sep = "")),
ylab = expression(paste(delta^15, "N (per mille)", sep = "")),
title = "Isospace plot of Inger et al Geese data"
)
# Run MCMC for each group
simmr_out <- simmr_ffvb(simmr_in)
# Print output
simmr_out
# Summarise output
summary(simmr_out, type = "quantiles", group = 1)
summary(simmr_out, type = "quantiles", group = c(1, 3))
summary(simmr_out, type = c("quantiles", "statistics"), group = c(1, 3))
# Plot - only a single group allowed
plot(simmr_out, type = "boxplot", group = 2, title = "simmr output group 2")
plot(simmr_out, type = c("density", "matrix"), grp = 6, title = "simmr output group 6")
# Compare groups
compare_groups(simmr_out, source = "Zostera", groups = 1:2)
compare_groups(simmr_out, source = "Zostera", groups = 1:3)
compare_groups(simmr_out, source = "U.lactuca", groups = c(4:5, 7, 2))
}
```