# Continuous Error Bands in Julia

Add continuous error bands to charts in Julia with Plotly.

Continuous error bands are a graphical representation of error or uncertainty as a shaded region around a main trace, rather than as discrete whisker-like error bars. They can be implemented in a manner similar to filled area plots using scatter traces with the fill attribute.

#### Filling within a single trace

In this example we show how to construct a trace that goes from low to high X values along the upper Y edge of a region, and then from high to low X values along the lower Y edge of the region. This trace is then 'self-filled' using fill='toself'.

using PlotlyJS

x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
y = [1, 2, 7, 4, 5, 6, 7, 8, 9, 10]
y_upper = [2, 3, 8, 5, 6, 7, 8, 9, 10, 11]
y_lower = [0, 1, 5, 3, 4, 5, 6, 7, 8, 9]

traces=[
scatter(
x=x,
y=y,
line=attr(color="rgb(0,100,80)"),
mode="lines"
),
scatter(
x=vcat(x, reverse(x)), # x, then x reversed
y=vcat(y_upper, reverse(y_lower)), # upper, then lower reversed
fill="toself",
fillcolor="rgba(0,100,80,0.2)",
line=attr(color="rgba(255,255,255,0)"),
hoverinfo="skip",
showlegend=false
)
]
plot(traces)

#### Filling between two traces

In this example we show how to construct the bounds of the band using two traces, with the lower trace using fill='tonexty' to fill an area up to the upper trace.

using PlotlyJS, DataFrames, CSV, HTTP

df = CSV.File(
) |> DataFrame

traces = [
scatter(
name="Measurement",
x=df[!, "Time"],
y=df[!, "10 Min Sampled Avg"],
mode="lines",
line=attr(color="rgb(31, 119, 180)"),
),
scatter(
name="Upper Bound",
x=df[!, "Time"],
y=df[!, "10 Min Sampled Avg"] .+ df[!, "10 Min Std Dev"],
mode="lines",
marker=attr(color="#444"),
line=attr(width=0),
showlegend=false
),
scatter(
name="Lower Bound",
x=df[!, "Time"],
y=df[!, "10 Min Sampled Avg"] .- df[!, "10 Min Std Dev"],
marker=attr(color="#444"),
line=attr(width=0),
mode="lines",
fillcolor="rgba(68, 68, 68, 0.3)",
fill="tonexty",
showlegend=false
)
]
layout = Layout(
yaxis_title="Wind speed (m/s)",
title="Continuous, variable value error bars",
hovermode="x"
)
plot(traces, layout)