plot_loss_heatmap: Plot observation-level contributions
In qshap: Fast Calculation of Feature Contributions in Boosting Trees

plot_loss_heatmap

R Documentation

Plot observation-level contributions

Description

Draws an efficient raster heatmap for selected observations, with a narrow total-contribution strip. For a local Q-SHAP result, the default display is 'local_rsq': observation-level contributions to the global R-squared decomposition, with legend values formatted as percentages. The underlying values remain unchanged. The diverging fill scale is centered at zero.

Usage

plot_loss_heatmap(
  loss,
  global_importance = NULL,
  feature_names = NULL,
  quantity = NULL,
  samples = NULL,
  n_show = 40,
  title = NULL,
  xtitle = "Feature",
  ytitle = "Observations",
  legend_title = NULL,
  low_color = "#2166AC",
  mid_color = "white",
  high_color = "#B2182B",
  rotation = 45,
  save_name = NULL
)

Arguments

`loss`	A numeric contribution matrix with observations in rows and features in columns, or a 'qshap_rsq'/'qshap_result' object produced with 'local = TRUE'.
`global_importance`	Optional numeric vector used to order features from most to least globally important. For a 'qshap_rsq' object, '$rsq' is used automatically. For a matrix, the default is '-colSums(loss)' when 'quantity = "loss"' and 'colSums(loss)' when 'quantity = "local_rsq"'.
`feature_names`	Optional feature labels. Defaults to 'colnames(loss)'.
`quantity`	Quantity to display when 'loss' is a Q-SHAP result: '"local_rsq"' for local contributions on the R-squared scale or '"loss"' for raw contributions to the change in squared loss. The default uses 'local_rsq' when available and otherwise falls back to 'loss'. For a matrix, this argument controls labels and the default feature-ordering rule; the matrix itself is displayed unchanged.
`samples`	Optional observation indices or row names/IDs to display. If 'NULL', informative observations are selected automatically from both extremes of the row sums.
`n_show`	Total number of observations selected automatically when 'samples = NULL'. Approximately half are taken from each extreme.
`title`	Optional plot title. For 'local_rsq', the default is "Observation-level contributions to the global R^2 decomposition".
`xtitle`	X-axis title.
`ytitle`	Y-axis title.
`legend_title`	Optional fill legend title. Defaults to "Local R^2 contribution" for 'local_rsq'.
`low_color`	Color for negative contributions.
`mid_color`	Color for zero.
`high_color`	Color for positive contributions.
`rotation`	Rotation angle for feature labels.
`save_name`	Optional output path without the '.pdf' extension.