---

name: rf-model-importance-analysis description: Use when you need a standardized R CLI workflow to train a two-class random forest model from an expression-like feature matrix, rank variable importance, and generate reproducible error and importance plots. NOT for regression tasks, multi-class classification, missing-value imputation, preprocessing, or remote data fetching. license: MIT author: AIPOCH

Source: https://github.com/aipoch/medical-research-skills

RF Model Importance Analysis

Quick Start

Use one of these three commands first, then consult the full argument table only if you need extra tuning.

1. Standard Run

Rscript scripts/main.R \
  --input_file tests/data/expression_matrix.csv \
  --group_file tests/data/group_info.csv \
  --case_group AR \
  --control_group Control \
  --output_dir tests/output/manual-test \
  --seed 42 \
  --timeout_seconds 300

2. Tuned Importance Run

Rscript scripts/main.R \
  --input_file tests/data/expression_matrix.csv \
  --group_file tests/data/group_info.csv \
  --case_group AR \
  --control_group Control \
  --output_dir tests/output/custom-importance \
  --seed 42 \
  --rf_ntree 800 \
  --rf_mtry 4 \
  --rf_imp_type 2 \
  --rf_imp_threshold 1 \
  --rf_top_n 8 \
  --rf_importance_top_n 8 \
  --timeout_seconds 300

3. Plot-Only Rerender

Run this only after a full analysis has already created output_dir/data/rf_result.rds.

Rscript scripts/main.R \
  --plot_only TRUE \
  --output_dir tests/output/manual-test \
  --seed 42 \
  --timeout_seconds 300

When to Read External Files

Situation	File to Read	Purpose
Need algorithm details	references/algorithm.md	Explain random forest modeling, importance metrics, assumptions, and result interpretation
Need to execute the analysis	scripts/main.R	Run the CLI entry point with a complete Rscript command
Encounter an error	references/troubleshooting.md	Map error codes to causes and fixes
Need CLI examples	references/cli-guide.md	See installation steps and runnable command examples
Need a runnable smoke test	tests/data/	Use the bundled small dataset for verification

Stop Conditions

Do not use this skill when any of the following is true:

• The task is regression, multiclass classification, time-series modeling, or remote data fetching.
• The input still requires imputation, normalization, batch correction, or other preprocessing.
• The feature matrix contains missing values, non-numeric feature columns, or mismatched sample IDs.

If one of those conditions applies, stop and hand off to a preprocessing or alternative modeling workflow before running this skill.

Usage

Before running the CLI, ensure the data is already cleaned for binary classification: samples in rows, numeric feature columns only, and no missing values. Imputation, normalization, and batch correction are outside this skill's scope.

Rscript scripts/main.R \
  --input_file ./input/expression_matrix.csv \
  --group_file ./input/group_info.csv \
  --case_group Case \
  --control_group Control \
  --output_dir output/basic-run \
  --seed 42 \
  --timeout_seconds 600

Arguments

Short	Long	Type	Default	Required	Description
-i	--input_file	character	none	yes, unless --plot_only TRUE	Expression matrix file with samples in rows and features in columns
-g	--group_file	character	none	yes, unless --plot_only TRUE	Group file with sample IDs in the first column
-c	--case_group	character	none	yes, unless --plot_only TRUE	Case group label
-r	--control_group	character	none	yes, unless --plot_only TRUE	Control group label
-o	--output_dir	character	output	yes	Output directory inside the skill root
-p	--plot_only	logical	FALSE	no	Reuse output_dir/data/rf_result.rds and regenerate plots without retraining
-s	--seed	integer	42	no	Random seed for reproducibility
-t	--timeout_seconds	integer	600	no	Elapsed time limit for the run
	--rf_ntree	integer	500	no	Number of trees in the random forest
	--rf_mtry	integer	NA	no	Variables sampled at each split; NA uses the package default
	--rf_nodesize	integer	NA	no	Minimum terminal node size; NA uses the package default
	--rf_imp_type	integer	1	no	Importance metric type passed to randomForest::importance; allowed values are 1 or 2
	--rf_imp_threshold	numeric	0	no	Minimum importance score retained in rf_top_features.csv
	--rf_top_n	integer	30	no	Maximum number of rows written to rf_top_features.csv
	--rf_error_xlab	character	Number of Trees	no	X-axis label for the RF error plot
	--rf_error_ylab	character	Error	no	Y-axis label for the RF error plot
	--rf_error_line_size	numeric	0.6	no	Line width for the RF error plot
	--rf_error_line_alpha	numeric	1	no	Line alpha for the RF error plot
	--rf_error_line_color	character	#6C85F9,#D9503D,#939DE4,#DEA441,#A2C6D6,#E9B9E1,#BDD69F,#EBC98A	no	Comma-separated line colors for non-OOB curves
	--rf_error_line_type	character	dashed	no	Line type for class-specific error curves
	--rf_error_line_oob_type	character	solid	no	Line type for the OOB curve
	--rf_error_legend_position	character	none	no	Legend position for the RF error plot
	--rf_error_border_color	character	black	no	Panel border color for the RF error plot
	--rf_error_border_fill	character	NA	no	Panel fill for the RF error plot; use NA or NULL as text
	--rf_error_border_size	numeric	0.8	no	Panel border width for the RF error plot
	--rf_error_base_size	numeric	14	no	Base font size for the RF error plot
	--rf_error_width	numeric	6	no	RF error plot width in inches
	--rf_error_height	numeric	5	no	RF error plot height in inches
	--rf_importance_sort	logical	TRUE	no	Sort variables in the importance plot
	--rf_importance_top_n	integer	10	no	Maximum number of variables shown in the importance plot
	--rf_importance_label_x_ann	logical	TRUE	no	Show x-axis tick labels in the importance plot
	--rf_importance_label_color	character	black	no	Text and point outline color in the importance plot
	--rf_importance_label_cex	numeric	0.9	no	Label size in the importance plot
	--rf_importance_point_cex	numeric	0.9	no	Point size in the importance plot
	--rf_importance_point_shape	integer	23	no	Point shape in the importance plot
	--rf_importance_point_fill	character	red	no	Point fill color in the importance plot
	--rf_importance_line_color	character	gray	no	Segment color in the importance plot
	--rf_importance_theme_border	logical	TRUE	no	Draw panel borders in the importance plot
	--rf_importance_theme_offset	numeric	0.2	no	Axis expansion factor in the importance plot
	--rf_importance_title	character	Variable Importance	no	Main title for the importance plot
	--rf_importance_title_x_ann	logical	TRUE	no	Show title and axis annotations in the importance plot
	--rf_importance_width	numeric	6	no	RF importance plot width in inches
	--rf_importance_height	numeric	5	no	RF importance plot height in inches

Input Format

Expression Matrix

• CSV or TSV.
• First column: sample IDs.
• Remaining columns: numeric features.
• Samples must be rows.
• Missing or non-numeric feature values are not allowed.

Example:

sample,HIF1A,NR4A1,SOCS1
S1,6.21,-1.34,2.01
S2,6.57,0.37,3.62
S3,7.05,2.12,5.01

Group File

• CSV or TSV.
• First column: sample IDs.
• One additional column must contain both the case and control labels.
• Exactly two groups are supported.

Example:

sample,group
S1,Case
S2,Case
S3,Control

Output Files

File	Format	Description
data/rf_result.rds	RDS	Serialized model bundle with the trained random forest and metadata
table/rf_feature_importance.csv	CSV	Full ranked feature-importance table using the selected importance metric
table/rf_top_features.csv	CSV	Filtered top feature table after applying --rf_imp_threshold and --rf_top_n
plot/rf_error_plot.pdf	PDF	Error curves across trees for OOB and class-specific classification error
plot/rf_importance_plot.pdf	PDF	Variable-importance plot generated by randomForest::varImpPlot()
session_info.txt	TXT	R version, platform, and package version information

Error Handling

• Successful runs exit with status code 0.
• Failed runs exit with status code 1.
• Error messages use standardized names such as SKILL_FILE_NOT_FOUND and SKILL_INVALID_PARAMETER.
• Output paths are validated so that --output_dir cannot write outside the skill root.
• The analysis never performs network requests and never executes user input through eval(), exec(), or system().

Common codes:

Error Code	Meaning
SKILL_FILE_NOT_FOUND	An input file or required plot-only artifact does not exist
SKILL_MISSING_COLUMNS	The input file does not contain the required columns
SKILL_EMPTY_DATA	An input file is empty or a required model table is unavailable
SKILL_INVALID_PARAMETER	A CLI argument, group setting, numeric constraint, or path is invalid
SKILL_SAMPLE_MISMATCH	Sample IDs do not match between the expression matrix and group file
SKILL_PACKAGE_NOT_FOUND	One or more required CRAN packages are missing

For detailed fixes, READ: references/troubleshooting.md

Testing

Help Check

Rscript scripts/main.R --help

Full Test Run

Rscript tests/run_tests.R

Direct Test Command

Rscript scripts/main.R \
  --input_file tests/data/expression_matrix.csv \
  --group_file tests/data/group_info.csv \
  --case_group AR \
  --control_group Control \
  --output_dir tests/output/manual-test \
  --seed 42 \
  --rf_ntree 200 \
  --rf_top_n 5 \
  --rf_importance_top_n 5 \
  --timeout_seconds 300