Plot ICA

This demo shows how to visualise ICA component topographies as scalp maps.

Why Plot ICA Topographies?

• Identify artefact components — blink and eye movement components have characteristic frontal patterns

• Verify decomposition — well-separated components should have distinct, interpretable scalp maps

• Select components — focus on a subset of components for inspection or removal

Key Functions

Function	Purpose	Typical Use
plot_topography(ica)	Plot all components	Full overview
plot_topography(ica, component_selection=...)	Plot selected components	Focused inspection

Key Parameters

Parameter	Default	Description
component_selection	components()	Which components to display
dims	auto	Grid size as (rows, cols)
use_global_scale	false	Share colour scale across all maps
colormap	:RdBu	Colour map for the topography
colorbar_plot	true	Show colorbars

What You'll Learn

1. Displaying all ICA component topographies in a grid

2. Selecting specific components by index or range

3. Adjusting grid layout and colour scaling

4. Using keyboard shortcuts to scale the colour range

Code Examples

Show Code

# Demo: Plotting ICA Component Topographies
# Shows how to visualise ICA component scalp maps as topographic plots,
# select specific components, and adjust display options.

using EegFun
# Note: EegFun.example_path() resolves bundled example data paths.
# When using your own data, simply pass the file path directly, e.g.:
# dat = EegFun.read_raw_data("/path/to/your/data.bdf")

#######################################################################
# LOAD DATA AND RUN ICA
#######################################################################

dat = EegFun.read_raw_data(EegFun.example_path("data/bdf/example1.bdf"))
layout = EegFun.read_layout(EegFun.example_path("layouts/biosemi/biosemi72.csv"))
EegFun.polar_to_cartesian_xy!(layout)
dat = EegFun.create_eegfun_data(dat, layout)

# highpass at 1 Hz for ICA (critical for good decomposition)
EegFun.highpass_filter!(dat, 1.0)

# average reference
EegFun.rereference!(dat, :avg)

# create additional Bool colum for v. extreme values
EegFun.is_extreme_value!(dat, 200)

# run ICA (excludinng the v. extreme samples)
ica = EegFun.run_ica(dat, sample_selection = EegFun.samples_not(:is_extreme_value_200))

#######################################################################
# BASIC TOPOGRAPHY GRID
#######################################################################

# plot all components in a grid
EegFun.plot_topography(ica, label_plot = false, point_plot = false)

#######################################################################
# SELECT SPECIFIC COMPONENTS
#######################################################################

# plot only the first 10 components
EegFun.plot_topography(ica, component_selection = EegFun.components(1:10))

#######################################################################
# CUSTOM GRID SIZE
#######################################################################

# control rows × columns layout
EegFun.plot_topography(ica, component_selection = EegFun.components(1:12), dims = (4, 3))

#######################################################################
# DISPLAY OPTIONS
#######################################################################

# shared colour scale across all components
EegFun.plot_topography(ica, component_selection = EegFun.components(1:10), use_global_scale = true)

# adjust colour map
EegFun.plot_topography(ica, component_selection = EegFun.components(1:6), colormap = :RdBu)

See Also

• API Reference