如何使Plotly双Y轴零点对齐且仅调整刻度标签？

需求：绘制包含柱状图和折线图的双Y轴图表，要求右侧Y轴（对应折线图）与左侧Y轴（对应柱状图）零点对齐，仅调整Y轴刻度标签，不修改原始数据展示。

原代码：

bar_trace = go.Bar(x=line_s['Year/Quarter'], y=line_s['CUR (€)'], name='CUR (€)')

line_trace1 = go.Scatter(x=line_s['Year/Quarter'], y=line_s['CUR PP'], name='CUR PP', yaxis='y2', 
                        mode='lines+markers', line=dict(color='orange'))

layout = go.Layout(title='test', 
                   yaxis=dict(title='CUR (€)'),
                   yaxis2=dict(title='CUR PP (%)', overlaying='y', side='right', tickmode="sync"),
                   legend=dict(x=1.06))

fig = go.Figure(data=[bar_trace, line_trace1], layout=layout)

fig.show()

图表示例：

解决方案 #

Plotly自带的tickmode="sync"仅同步刻度数量，无法实现零点对齐。要达成需求，需通过计算两个Y轴数据的极值，手动调整轴的range参数，让零点在同一水平线上。

步骤与修改后代码 #

1. 获取两组数据的极值，计算零点到两端的范围比例
2. 根据比例调整右侧Y轴的范围，确保与左侧Y轴零点对齐

完整代码如下：

import plotly.graph_objects as go

# 假设line_s是已加载的数据集
bar_trace = go.Bar(x=line_s['Year/Quarter'], y=line_s['CUR (€)'], name='CUR (€)')
line_trace1 = go.Scatter(x=line_s['Year/Quarter'], y=line_s['CUR PP'], name='CUR PP', yaxis='y2', 
                        mode='lines+markers', line=dict(color='orange'))

# 获取两个系列的Y轴极值
y1_min = line_s['CUR (€)'].min()
y1_max = line_s['CUR (€)'].max()
y2_min = line_s['CUR PP'].min()
y2_max = line_s['CUR PP'].max()

# 计算左侧Y轴正负方向的范围（以零点为基准）
y1_range_neg = abs(y1_min) if y1_min < 0 else 0
y1_range_pos = y1_max if y1_max > 0 else 0

# 计算右侧Y轴正负方向的范围
y2_range_neg = abs(y2_min) if y2_min < 0 else 0
y2_range_pos = y2_max if y2_max > 0 else 0

# 计算比例，确保零点对齐
ratio_neg = y1_range_neg / y2_range_neg if y2_range_neg != 0 else 1
ratio_pos = y1_range_pos / y2_range_pos if y2_range_pos != 0 else 1

# 确定右侧Y轴的新范围
if y2_range_neg > 0 and y2_range_pos > 0:
    target_ratio = max(ratio_neg, ratio_pos)
    y2_new_min = -y1_range_neg / target_ratio
    y2_new_max = y1_range_pos / target_ratio
elif y2_range_neg > 0:
    y2_new_min = -y1_range_neg / ratio_neg
    y2_new_max = 0
else:
    y2_new_min = 0
    y2_new_max = y1_range_pos / ratio_pos

# 更新布局
layout = go.Layout(title='test', 
                   yaxis=dict(title='CUR (€)', range=[-y1_range_neg, y1_range_pos]),
                   yaxis2=dict(title='CUR PP (%)', overlaying='y', side='right', range=[y2_new_min, y2_new_max]),
                   legend=dict(x=1.06))

fig = go.Figure(data=[bar_trace, line_trace1], layout=layout)
fig.show()

说明 #

• 该方案仅调整Y轴的刻度范围和标签，完全不修改原始数据的展示
• 通过计算正负范围的比例，确保两个Y轴的零点精确对齐
• 兼容单侧有负值、双侧都有负值或无负值的多种数据场景

内容的提问来源于stack exchange，提问作者hvahva