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Interactive Analysis with the cellreportR Shiny App

Source: vignettes/shiny-app.Rmd
shiny-app.Rmd

The bundled application walks the same pipeline as the package functions — read segmented exports, specify the design, apply quality control at cell and unit level, standardize, estimate effect sizes with confidence intervals at both levels, export a report — in a browser rather than in a script. It is meant for laboratory personnel without an R background, and for anyone who wants to look at a data set before writing the script.

Every analytical step in the app delegates to an exported cr_* function, so the app and a scripted analysis produce the same numbers.

Launching 

library(cellreportR)

cr_run_app()                      # starts empty; example data is one click away
cr_run_app(experiment = my_exp)   # start from an experiment already in session

cr_run_app() needs shiny, bslib, DT and ggplot2, all of which are listed under Suggests; a missing one raises an error naming it. The upload limit is raised to 512 MB for the duration of the session, because segmented single-cell exports routinely exceed the Shiny default of 5 MB, and the previous value is restored on exit.

args(cr_run_app)
#> function (experiment = NULL, max_upload_mb = 512, launch_browser = interactive(), 
#>     ...) 
#> NULL

Layout

The page has four fixed regions:

  • a sidebar, always visible, holding the three things every tab depends on — where the data comes from, which marker channel the analysis targets, and which level of the design is the control;
  • a status card with a running log of what the app has done, so an analysis can be reconstructed afterwards;
  • the tab strip, in analysis order;
  • an About card.

The sidebar

  1. Data source — upload one or more segmented exports, or type the path of a directory and let the app read it with a file pattern and an optional recursive scan. Load example data fills the app with a synthetic multi-compound screen (cr_example_screen()) when there is nothing to hand.
  2. Design — upload a design table (.csv, .tsv or .xlsx), or build one in the Design tab.
  3. Analysis target — the marker channel and the control level. Every tab downstream reads these two selectors, so changing the control level here changes what every later tab compares against.

The whole experiment can be downloaded as an .rds from the sidebar at any point, which is the bridge from the app back to a script.

The tabs

Tab What it does Backed by
Data Cell table, the files that were read, detected channels cr_read_cells(), cr_read_exports()
Design Derive one design row per unit, assign treatment levels, build the experiment cr_build_experiment()
Quality control Cell filters, doublet removal, and the per-unit gate against each unit’s own control cr_qc_filter(), cr_qc_doublets(), cr_qc_gate(), cr_apply_gate()
Normalisation Robust z-score, z-score, control ratio, background subtraction or quantile, optionally within a batch variable cr_normalize(), cr_correct_batch()
Effect sizes Forest plot and effect table at unit or cell level cr_effect_grid(), cr_plot_forest()
Dose-response 4PL / 3PL / linear fit with the fitted parameters cr_dose_response(), cr_ic50()
Figures Plate map, intensity by treatment, histogram, QC dashboard, spatial map cr_plot_plate() and friends
Report Pairwise comparisons, queued figures, and the exported report cr_report(), cr_render_report()

The Quality control tab is the one worth spending time in. Its sub-panels are the exclusion table, the disputed verdicts (units whose verdict depends on whether the control’s median or mean is used as the threshold), the gate figure, the area distribution and the QC log. Rows selected in the exclusion table are dropped together with the units that fail the gate, which is the interactive form of the reviewed exclusion list shown in vignette("end-to-end").

Cross-tab state

The app keeps everything it knows in one shiny::reactiveValues() store: the cells, the design, the assembled experiment, the state it was imported in, the gate, the effect grid, the results and the queued figures. Quality control, normalisation and analysis replace the experiment in that store, so every downstream tab reacts without any tab reaching into another.

Two consequences worth knowing:

  • Reset is real. Reset to imported state in the Quality control and Normalisation tabs restores the experiment as it was imported, not the previous step.
  • Figures are queued, not saved. Queue for report adds the current figure to the report assembly; the Report tab exports the queue.

Deployment

The user interface, the server and every helper live inside the package namespace, so the app can be driven in-process by shiny::testServer() as well as from a browser. inst/shiny/cellreportR/ holds only the www/ assets and a thin app.R shim for deployment on a Shiny server.