Error Bars in Julia

How to add error-bars to charts in Julia with Plotly.

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Error Bars

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

df[!, "e"] = df[!, "sepal_width"] ./ 100

plot(
    df, x=:sepal_width, y=:sepal_length, color=:species,
    mode="markers",
    error_x=attr(type="data", array=:e, visible=true),
    error_y=attr(type="data", array=:e, visible=true),
)

Asymmetric Error Bars

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

df[!, "e_plus"] = df[!, "sepal_width"] ./ 100
df[!, "e_minus"] = df[!, "sepal_width"] ./ 40
plot(
    df, x=:sepal_width, y=:sepal_length, color=:species,
    mode="markers",
    error_y=attr(type="data", array=:e_plus, arrayminus=:e_minus, visible=true),
)

Error Bars as a Percentage of the y Value

using PlotlyJS

plot(scatter(
    x=[0, 1, 2], y=[6, 10, 2], mode="markers+lines",
    error_y=attr(
        type="percent", # value of error bar given as percentage of y value
        value=50,
        visible=true
    )
))

Asymmetric Error Bars with a Constant Offset

using PlotlyJS

plot(scatter(
    x=[1, 2, 3, 4],
    y=[2, 1, 3, 4],
    mode="markers+lines",
    error_y=attr(
        type="percent",
        symmetric=false,
        value=15,
        valueminus=25
    )
))

Horizontal Error Bars

using PlotlyJS

plot(scatter(
    x=[1, 2, 3, 4],
    y=[2, 1, 3, 4],
    mode="markers+lines",
    error_x=attr(
        type="percent",
        value=15
    )
))

Bar Chart with Error Bars

using PlotlyJS

plot([
    bar(
        name="Control",
        x=["Trial 1", "Trial 2", "Trial 3"], y=[3, 6, 4],
        error_y=attr(type="data", array=[1, 0.5, 1.5])
    ),
    bar(
        name="Experimental",
        x=["Trial 1", "Trial 2", "Trial 3"], y=[4, 7, 3],
        error_y=attr(type="data", array=[0.5, 1, 2])
    )
])

Colored and Styled Error Bars

using PlotlyJS

x_theo = range(-4, stop=4, length=100)
sincx = sinc.(x_theo)
x = [-3.8, -3.03, -1.91, -1.46, -0.89, -0.24, -0.0, 0.41, 0.89, 1.01, 1.91, 2.28, 2.79, 3.56]
y = [-0.02, 0.04, -0.01, -0.27, 0.36, 0.75, 1.03, 0.65, 0.28, 0.02, -0.11, 0.16, 0.04, -0.15]

trace1 = scatter(
    x=x_theo, y=sincx,
    name="sinc(x)"
)

trace2 = scatter(
    x=x, y=y,
    mode="markers",
    name="measured",
    error_y=attr(
        type="constant",
        value=0.1,
        color="purple",
        thickness=1.5,
        width=3,
    ),
    error_x=attr(
        type="constant",
        value=0.2,
        color="purple",
        thickness=1.5,
        width=3,
    ),
    marker=attr(color="purple", size=8)
)

plot([trace1, trace2])

Reference

See https://plotly.com/julia/reference/scatter/ for more information and chart attribute options!