绘图中的对数色标

Question

我正在尝试使用Plotly和用一些异常值来可视化数据Python3。异常值导致色标图例看起来很糟糕：只有很少的高数据点，但图例看起来很糟糕：2k 和 10k 之间的空间太大。

所以问题是，如何更改右侧“颜色图例”的外观（见下图），以便它主要显示 0 到 2k 之间的差异？不幸的是，无法从这个文档文件中得到答案

示例代码（jupyter notebook）：

import numpy as np
from plotly.offline import download_plotlyjs, init_notebook_mode, iplot
from plotly.graph_objs import *
init_notebook_mode()

x = np.random.randn(100,1) + 3
y = np.random.randn(100,1) + 10
x = np.reshape(x, 100)
y = np.reshape(y, 100)

color = np.random.randint(0,1000, [100])
color[[1,3,5]] = color[[1,3,5]] + 10000 # create outliers in color var

trace = Scatter(
    x = x,
    y = y,
    mode = 'markers',
    marker=dict(
        color = color,
        showscale=True,
        colorscale = [[0, 'rgb(166,206,227, 0.5)'],
                      [0.05, 'rgb(31,120,180,0.5)'],
                      [0.1, 'rgb(178,223,138,0.5)'],
                      [0.15, 'rgb(51,160,44,0.5)'],
                      [0.2, 'rgb(251,154,153,0.5)'],
                      [1, 'rgb(227,26,28,0.5)']
                     ]
    )
)

fig = Figure(data=[trace])
iplot(fig)

我在找什么：

Answer 1

您可以通过自定义colorscale、cmin和cmax属性以在 2000 处进行离散颜色变化来实现我认为您想要的目标。然后您可以自定义colorbar.tickvals将边界标记为 2000。请参阅https://plot.ly/python/reference /#scatter-marker-colorbar。

import numpy as np
from plotly.offline import download_plotlyjs, init_notebook_mode, iplot
from plotly.graph_objs import *
init_notebook_mode()

x = np.random.randn(100,1) + 3
y = np.random.randn(100,1) + 10
x = np.reshape(x, 100)
y = np.reshape(y, 100)

color = np.random.randint(0,1000, [100])
color[[1,3,5]] = color[[1,3,5]] + 10000 # create outliers in color var

bar_max = 2000
factor = 0.9  # Normalized location where continuous colorscale should end

trace = Scatter(
    x = x,
    y = y,
    mode = 'markers',
    marker=dict(
        color = color,
        showscale=True,
        cmin=0,
        cmax= bar_max/factor,
        colorscale = [[0, 'rgb(166,206,227, 0.5)'],
                      [0.05, 'rgb(31,120,180,0.5)'],
                      [0.2, 'rgb(178,223,138,0.5)'],
                      [0.5, 'rgb(51,160,44,0.5)'],
                      [factor, 'rgb(251,154,153,0.5)'],
                      [factor, 'rgb(227,26,28,0.5)'],
                      [1, 'rgb(227,26,28,0.5)']
                     ],
        colorbar=dict(
            tickvals = [0, 500, 1000, 1500, 2000],
            ticks='outside'
        )
    )
)

fig = Figure(data=[trace])
iplot(fig)

^{新的数字结果}