Frequently Asked Questions

ssdtools Team

2023-09-07

How can I plot the model averaged fit with individual fits?

library(ssddata)
library(ssdtools)
library(ggplot2)

dist <- ssdtools::ssd_fit_dists(ssddata::ccme_boron)
pred <- predict(dist, ci = FALSE)

ssdtools::ssd_plot_cdf(dist) +
  geom_line(data = pred, aes(x = est, y = percent/100))

How do I fit distributions to multiple groups such taxa and/or chemicals?

An elegant approach using some tidyverse packages is demonstrated below.

library(ssddata)
library(ssdtools)
library(ggplot2)
library(dplyr)
library(tidyr)
library(purrr)

boron_preds <- nest(ccme_boron, data = c(Chemical, Species, Conc, Units)) %>%
  mutate(
    Fit = map(data, ssd_fit_dists, dists = "lnorm"),
    Prediction = map(Fit, predict)
  ) %>%
  unnest(Prediction)

The resultant data and predictions can then be plotted as follows.

ssd_plot(ccme_boron, boron_preds, xlab = "Concentration (mg/L)", ci = FALSE) +
  facet_wrap(~Group)

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