digraph ICAdiagram {
    /* LAYOUT CONTROL */
    rankdir=LR
    newrank=true
    ranksep=0.75
    clusterrank=local

    /* GLOBAL STYLES */
    splines=true
    fontsize=20
    fontname="Source Code Pro"

    node [style="filled"
          fontsize=18
          fontname="Source Sans Pro"]

    edge [arrowsize=1.2
          penwidth=2.5
          color="gray50"
          fontsize=12
          fontname="Source Code Pro"]

    /* starting nodes */
    sensor [label="Sensor data" shape="box" fillcolor="#bbbbbb"]
    cov [label="Noise cov" shape="box" fillcolor="#bbbbbb"]

    /* ICA.FIT() */
    subgraph cluster_0 {
        label="ICA.fit()"
        color="#009988"
        fontcolor="#009988"
        penwidth=1.5


        /* PRE-WHITENING */
        subgraph cluster_1 {
            label="Whitening"
            style="dashed"
            fontname="Source Sans Pro"
            color="gray50"
            fontcolor="gray50"
            /* nodes & edges */
            pre [label="Pre-\nwhiten" fontsize=11 shape="circle" fillcolor="#ee7733"]
            pre -> pca
            pca        [label="PCA"                   shape="circle" fillcolor="#ee7733"]
            pcs        [label="Principal\ncomponents" shape="box"    fillcolor="#33bbee"]
            pca -> pcs
        }

        /* nodes & edges */
        ica        [label="ICA"                     shape="circle" fillcolor="#ee7733"]
        ics        [label="Independent\ncomponents" shape="box"    fillcolor="#33bbee"]
        ica -> ics [label="n_components\r"]
    }

    /* ICA.APPLY() */
    subgraph cluster_2 {
        label="ICA.apply()"
        color="#ee3377"
        fontcolor="#ee3377"
        penwidth=1.5
        /* ending node */
        recon [label="Reconstructed\nsensor data" shape="box" fillcolor="#bbbbbb"]
    }

    /* subgraph-crossing edges */
    sensor -> pre  [label="all sensor channels\r" fontsize=14 fontname="Source Sans Pro"]
    cov -> pre     [label="covariance or std. dev.\r" fontsize=14 fontname="Source Sans Pro"]
    pcs -> ica     [label="n_components\l"]
    ics -> recon   [constraint=false color="#ee3377"
                    xlabel="Retained ICs:\ln_components -\llen(ICA.exclude)\l"]
    pcs -> recon   [constraint=false color="#ee3377"
                    xlabel="PCA residual:\ln_pca_components\l- n_components\l"]

    /* position recon box where we want it */
    { rank="same" recon ica }
}