Mean and CV Flutter Operator

Description

The mean_and_cv_flutter_operator is a Flutter web app used for creating CV plots, and fitting the variation as a function of intensity to the Two Component Error Model. This is the Flutter/WASM replacement for the original mean_and_cv_shiny_operator.

Usage

Input projection	.
row	represents the variables (e.g. ID)
col	represents the category (e.g. barcode, Sample Name)
y-axis	measurement value
color	color (e.g. barcode, Sample Name)

Output relations	.
Operator view	view of the Flutter web application

Details

The operator creates CV (Coefficient of Variation), SNR (Signal-to-Noise Ratio), and SD (Standard Deviation) plots. It fits the Two Component Error Model to the data and displays the fit curve overlaid on the scatter plot.

The crosstab grid is laid out as follows:

• Rows (supergroups): determined by the color projection
• Columns (test conditions): determined by the col projection
• Each pane shows a scatter plot of the selected metric (CV, SNR, or SD) against mean intensity
• The "Combine Groups" toggle collapses all panes into a single combined view with per-pane coloring

Two Component Error Model: variance = σ₀² + CV₁² × mean²

The model is fitted iteratively using quantile-based thresholds to classify points as low-signal (used to estimate σ₀) and high-signal (used to estimate CV₁ from log-variance). SNR is reported in dB as -10 × log₁₀(CV₁).

Controls

• Display: Chart title, plot type (CV/SNR/SD), model fit toggle, combine groups toggle
• Axes: Log x-axis, manual X/Y axis limits with auto checkboxes
• Model Fitting: High and low signal quantile threshold sliders (0.0–1.0)
• Export: PNG and PDF download with per-pane size controls (width × height in pixels)

Context Detection

The app detects whether it is running embedded in Tercen or standalone:

• Embedded (?taskId=xxx in URL): connects to the Tercen API to load real crosstab data
• Standalone (no taskId): falls back to bundled CSV example data and shows a top bar with "FULL SCREEN MODE" badge

Building

# Get dependencies
flutter pub get

# Build for Tercen deployment (WASM)
flutter build web --wasm --release

# Run locally in Chrome
flutter run -d chrome

The built output is served from build/web as configured in operator.json.

See Also

mean_and_cv_shiny_operator mean_operator mean_sd_operator