Contour Plots in Julia
How to make Contour plots in Julia with Plotly.
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Basic Contour Plot
A 2D contour plot shows the contour lines of a 2D numerical array z, i.e. interpolated lines of isovalues of z.
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]'
))Setting X and Y Coordinates in a Contour Plot
using PlotlyJS
plot(contour(
x=[-9, -6, -5 , -3, -1], # horizontal axis
y=[0, 1, 4, 5, 7], # vertical axis
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]'
))Colorscale for Contour Plot
using PlotlyJS
plot(contour(
colorscale="Electric",
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]'
))Customizing Size and Range of a Contour Plot's Contours
using PlotlyJS
plot(contour(
z=z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
colorscale="Hot",
contours_start=0,
contours_end=8,
contours_size=2
))
Customizing Spacing Between X and Y Axis Ticks
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
dx=10, x0=5, dy=10, y0=10,
))Connect the Gaps Between None Values in the Z Matrix
using PlotlyJS
p = make_subplots(
rows=2, cols=2,
column_titles=["connectgaps = False"; "connectgaps = True"],
row_titles=["Contour map"; "Heatmap"]
)
z = [
[missing, missing, missing, 12, 13, 14, 15, 16],
[missing, 1, missing, 11, missing, missing, missing, 17],
[missing, 2, 6, 7, missing, missing, missing, 18],
[missing, 3, missing, 8, missing, missing, missing, 19],
[5, 4, 10, 9, missing, missing, missing, 20],
[missing, missing, missing, 27, missing, missing, missing, 21],
[missing, missing, missing, 26, 25, 24, 23, 22]
]
add_trace!(p, contour(z=z, showscale=false), row=1, col=1)
add_trace!(p, contour(z=z, showscale=false, connectgaps=true), row=1, col=2)
add_trace!(p, heatmap(z=z, showscale=false, zsmooth="best"), row=2, col=1)
add_trace!(p, heatmap(z=z, showscale=false, connectgaps=true, zsmooth="best"), row=2, col=2)
pSmoothing the Contour lines
using PlotlyJS
z = [
2 4 7 12 13 14 15 16
3 1 6 11 12 13 16 17
4 2 7 7 11 14 17 18
5 3 8 8 13 15 18 19
7 4 10 9 16 18 20 19
9 10 5 27 23 21 21 21
11 14 17 26 25 24 23 22
]'
p = make_subplots(
rows=1, cols=2, column_titles=["Without Smoothing"; "With Smoothing"]
)
add_trace!(p, contour(z=z, line_smoothing=0), row=1, col=1)
add_trace!(p, contour(z=z, line_smoothing=0.85), row=1, col=2)
pSmooth Contour Coloring
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
# heatmap gradient coloring is applied between each contour level
contours_coloring="heatmap" # can also be "lines", or "none"
))Contour Line Labels
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
# heatmap gradient coloring is applied between each contour level
contours=attr(
coloring ="heatmap",
showlabels = true, # show labels on contours
labelfont = attr( # label font properties
size = 12,
color = "white",
)
)
))Contour Lines
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
contours_coloring="lines",
line_width=2,
))Custom Contour Plot Colorscale
using PlotlyJS
# Valid color strings are CSS colors, rgb or hex strings
colorscale = [[0, "gold"], [0.5, "mediumturquoise"], [1, "lightsalmon"]]
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
colorscale=colorscale,
))
Color Bar Title
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
colorbar=attr(
title="Color bar title", # title here
titleside="right",
titlefont=attr(
size=14,
family="Arial, sans-serif"
)
)
))Color Bar Size for Contour Plots
In the example below, both the thickness (given here in pixels) and the length (given here as a fraction of the plot height) are set.
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
colorbar=attr(
thickness=25,
thicknessmode="pixels",
len=0.6,
lenmode="fraction",
outlinewidth=0
)
))Styling Color Bar Ticks for Contour Plots
using PlotlyJS
plot(contour(
z=[
10 10.625 12.5 15.625 20
5.625 6.25 8.125 11.25 15.625
2.5 3.125 5. 8.125 12.5
0.625 1.25 3.125 6.25 10.625
0 0.625 2.5 5.625 10
]',
colorbar=attr(
nticks=10, ticks="outside",
ticklen=5, tickwidth=1,
showticklabels=true,
tickangle=0, tickfont_size=12
)
))Reference
See https://plotly.com/julia/reference/contour/ for more information and chart attribute options!