    library(ggcyto)
    data(GvHD)
    fs <- GvHD[subset(pData(GvHD), Patient %in%5:7 & Visit %in% c(5:6))[["name"]]]
    fr <- fs[[1]]

### 1d histogram/densityplot

`ggcyto` wrapper will construct the `ggcyto` object that inherits from `ggplot` class.

    p <- ggcyto(fs, aes(x = `FSC-H`))
    class(p)

    ## [1] "ggcyto_flowSet"
    ## attr(,"package")
    ## [1] "ggcyto"

    is(p, "ggplot")

    ## [1] TRUE

Since only one dimension is specified, we can add any 1d geom layer

    p1 <- p + geom_histogram()
    p1

As shown, data is facetted by samples name automatically (i.e `facet_wrap(~name)`).

We can overwrite the default faceting by any variables that are defined in `pData`

    pData(fs)

    ##       Patient Visit Days Grade  name
    ## s5a05       5     5   19     3 s5a05
    ## s5a06       5     6   26     3 s5a06
    ## s6a05       6     5   19     3 s6a05
    ## s6a06       6     6   27     3 s6a06
    ## s7a05       7     5   21     3 s7a05
    ## s7a06       7     6   28     3 s7a06

    p1 + facet_grid(Patient~Visit)

To display 1d density

    p + geom_density()

Fill the same color

    p + geom_density(fill = "black")

Fill different colors

    ggcyto(fs, aes(x = `FSC-H`, fill = name)) + geom_density(alpha = 0.2)

Or plot in the same panel by using `ggplot` directly (thus removing the default facetting effect)

    ggplot(fs, aes(x = `FSC-H`, fill = name)) + geom_density(alpha = 0.2)

### stacked density plot

    #you can use ggridges package to display stacked density plot
    require(ggridges)
    #stack by fcs file ('name')
    p + geom_density_ridges(aes(y = name)) + facet_null() #facet_null is used to remove the default facet_wrap (by 'name' column)

    #or to stack by Visit and facet by patient
    p + geom_density_ridges(aes(y = Visit)) + facet_grid(~Patient)

### 2d scatter/dot plot

    # 2d hex
    p <- ggcyto(fs, aes(x = `FSC-H`, y =  `SSC-H`))
    p <- p + geom_hex(bins = 128)
    p

A default `scale_fill_gradientn` is applied to 2d hexbin plot.

To add limits

    p <- p + ylim(c(10,9e2)) + xlim(c(10,9e2))
    p

To overwrite the default fill gradien

    p + scale_fill_gradientn(colours = rainbow(7), trans = "sqrt")

    p + scale_fill_gradient(trans = "sqrt", low = "gray", high = "black")

### Add `geom_gate` and `geom_stats` layers

Firstly we create an `ellipsoidGate` with a data-driven method provided by `flowStats` package.

    # estimate a lymphGate (which is an ellipsoidGate) for each sample
    lg <- flowStats::lymphGate(fs, channels=c("FSC-H", "SSC-H"),scale=0.6)
    # apply the ellipsoidGates to their corresponding samples
    fres <- filter(fs, lg)

Then pass the gates to the gate layer

    p + geom_gate(lg)

We can also plot the `rectangleGate`, this time we simply replicate a static gate across samples:

    rect.g <- rectangleGate(list("FSC-H" =  c(300,500), "SSC-H" = c(50,200)))
    rect.gates <- sapply(sampleNames(fs), function(sn)rect.g)

Similarly, supply the list of gates to the `geom_gate` layer

    p + geom_gate(rect.gates)

Stats layer can be added on top of gate

    p + geom_gate(rect.gates) + geom_stats(size = 3)

The `percentage` of the gated population over its parent is displayed as `geom_label`. Alternatively cell `count` can be displayed by setting `type` argument in `geom_stats` function.

Here is another example of displaying the 1d gate generated by the automated gating method `gate_mindensity` from `openCyto` package.

    den.gates.x <- fsApply(fs, openCyto::gate_mindensity, channel = "FSC-H", gate_range = c(100, 300), adjust = 1)
    p + geom_gate(den.gates.x) + geom_stats()

`geom_gate` layer supports the 1d gate on either dimension, which means it automatically determines between the vertical or horizontal lines based on the gate dimension and given `aes`.

    den.gates.y <- fsApply(fs, openCyto::gate_mindensity, channel = "SSC-H", gate_range = c(100, 500), adjust = 1, positive = FALSE)

    p + geom_gate(den.gates.y) + geom_stats(value = lapply(rect.gates, function(g)0.1))

Here we also demenstrated the option of passing the precalculated arbitary stats value to `geom_stats` lay instead of letting it compute on the fly,

We can also put the 1d gate on density plot

    ggcyto(fs, aes(x = `FSC-H`)) + geom_density(fill = "black", aes(y = ..scaled..)) + geom_gate(den.gates.x)  + geom_stats(type = "count")

Without supplying `data` for `geom_stats`, we add stats layer for all the gate layers implicitly

    p + geom_gate(lg) + geom_gate(rect.gates) + geom_stats(size = 3)

Or we can add stats layer specificly just for one of the gate layer

    p + geom_gate(lg) + geom_gate(rect.gates) + geom_stats(gate = lg, size = 3)

Although `ggcyto` object is fully ggplot-compatible in terms of adding layers and parameters, its data slot MAY NOT be fully fortified to data.frame before it is printed/plotted.

    class(p)

    ## [1] "ggcyto_flowSet"
    ## attr(,"package")
    ## [1] "ggcyto"

    class(p$data)

    ## [1] "flowSet"
    ## attr(,"package")
    ## [1] "flowCore"

To convert it to a pure ggplot object, use `as.ggplot` function:

    p <- as.ggplot(p)

    class(p)

    ## [1] "gg"     "ggplot"

    class(p$data)

    ## [1] "data.table" "data.frame"