Plotly：如何控制双 y 轴前面的轨迹？

Question

I have a double y-axis plot that looks like this:

In this example, the bars are on the secondary y-axis. However, I want the line to be in front of the bars. I thought doing yaxis2=dict(overlaying='y1') would solve the issue, but nothing different occurred. The only hackish solution I have come up with so far is to turn the opacity down on the bars so you can actually see the line. Surely though there is a way to fix this that I am missing.

Answer 1

Answer:

The trace on the secondary y-axis will appear on top. No matter if its a go.Scatter() trace or a go.Bar() trace

Details:

The overlaying attribute only applies to cases with more than two y-axes, like here :

From the docs you can see that:

overlaying Parent: layout.xaxis Type: enumerated , one of ( "free" | "/^x([2-9]|[1-9][0-9]+)?$/" | "/^y([2-9]|[1-9][0-9]+)?$/" ) If set a same-letter axis id, this axis is overlaid on top of the corresponding same-letter axis, with traces and axes visible for both axes. If "False", this axis does not overlay any same-letter axes. In this case, for axes with overlapping domains only the highest-numbered axis will be visible.

So, how about your case? Generally, traces are displayed in the order that they are added to the fig . But not when it comes to a figure with two y-axes. It seems you will have to switch with trace you're displaying on the primary axis. The first snippet produces a figure with bars on the primary axis. The second snippet producds a figure with bars on the secondary axis. This also determines which trace is shown on top.

Code 1:

import plotly.graph_objects as go
from plotly.subplots import make_subplots

# Create figure with secondary y-axis
fig = make_subplots(specs=[[{"secondary_y": True}]])

# Add traces
fig.add_trace(
    go.Bar(x=[1, 2, 3], y=[40, 50, 60], name="yaxis data"),
    secondary_y=True,
)

fig.add_trace(
    go.Scatter(x=[1, 2, 3], y=[45, 50, 45], name="yaxis2 data"),
    secondary_y=False,
)

fig.show()

Plot 1:

Code 2:

import plotly.graph_objects as go
from plotly.subplots import make_subplots

# Create figure with secondary y-axis
fig = make_subplots(specs=[[{"secondary_y": True}]])

# Add traces
fig.add_trace(
    go.Bar(x=[1, 2, 3], y=[40, 50, 60], name="yaxis data"),
    secondary_y=False,
)

fig.add_trace(
    go.Scatter(x=[1, 2, 3], y=[45, 50, 45], name="yaxis2 data"),
    secondary_y=True,
)


fig.show()

Plot 2: