2.1　绘图方法

figure(**kwargs)对象提供多种绘图方法(见1.3节)，而这些方法的实现大都基于Bokeh.models接口。本节将展示些基本图形的绘制方法。

代码示例　2-1

1. import numpy as np

2. from bokeh.layouts import gridplot

3. # 数据

4. N = 9

5. x = np.linspace(-2, 2, N)

6. y = x**2

7. sizes = np.linspace(10, 20, N)

8. xpts = np.array([-.09, -.12, .0, .12, .09])

9. ypts = np.array([-.1, .02, .1, .02, -.1])

10. # 画布列表

11. figures = []

12. p = figure(title="annular_wedge")

13. p.annular_wedge(x, y, 10, 20, 0.6, 4.1, color="#8888ee",

14. inner_radius_units="screen", outer_radius_units="screen")

15. figures.append(p)

16. p = figure(title="annulus")

17. p.annulus(x, y, 10, 20, color="#7FC97F",

18. inner_radius_units="screen", outer_radius_units = "screen")

19. figures.append(p)

20. p = figure(title="arc")

21. p.arc(x, y, 20, 0.6, 4.1,

22. radius_units="screen", color="#BEAED4", line_width=3)

23. figures.append(p)

24. p = figure(title="bezier")

25. p.bezier(x, y, x+0.2, y, x+0.1, y+0.1, x-0.1, y-0.1,

26. color="#D95F02", line_width=2)

27. figures.append(p)

28. p = figure(title="circle")

29. p.circle(x, y, radius=0.1, color="#3288BD")

30. figures.append(p)

31. p = figure(title="ellipse")

32. p.ellipse(x, y, 15, 25, angle=-0.7, color="#1D91C0",

33. width_units="screen", height_units="screen")

34. figures.append(p)

35. p = figure(title="line")

36. p.line(x, y, color="#F46D43")

37. figures.append(p)

38. p = figure(title="multi_line")

39. p.multi_line([xpts+xx for xx in x], [ypts+yy for yy in y], color="#8073AC",

line_width=2)

40. figures.append(p)

41. p = figure(title="multi_polygons")

42. p.multi_polygons([[[xpts*2+xx, xpts+xx]] for xx in x], [[[ypts*3+yy,

ypts+yy]] for yy in y], color="#FB9A99")

43. figures.append(p)

44. p = figure(title="oval")

45. p.oval(x, y, 15, 25, angle=-0.7, color="#1D91C0",

46. width_units="screen", height_units="screen")

47. figures.append(p)

48. p = figure(title="patch")

49. p.patch(x, y, color="#A6CEE3")

50. figures.append(p)

51. p = figure(title="patches")

52. p.patches([xpts+xx for xx in x], [ypts+yy for yy in y], color="#FB9A99")

53. figures.append(p)

54. p = figure(title="quad")

55. p.quad(x, x-0.1, y, y-0.1, color="#B3DE69")

56. figures.append(p)

57. p = figure(title="quadratic")

58. p.quadratic(x, y, x+0.2, y, x+0.1, y+0.1, color="#4DAF4A", line_width=3)

59. figures.append(p)

60. p = figure(title="ray")

61. p.ray(x, y, 45, -0.7, color="#FB8072", line_width=2)

62. figures.append(p)

63. p = figure(title="rect")

64. p.rect(x, y, 10, 20, color="#CAB2D6", width_units="screen", height_units="screen")

65. figures.append(p)

66. p = figure(title="segment")

67. p.segment(x, y, x-0.1, y-0.1, color="#F4A582", line_width=3)

68. figures.append(p)

69. p = figure(title="square")

70. p.square(x, y, size=sizes, color="#74ADD1")

71. figures.append(p)

72. p = figure(title="wedge")

73. p.wedge(x, y, 15, 0.6, 4.1, radius_units="screen", color="#B3DE69")

74. figures.append(p)

75. p = figure(title="circle_x")

76. p.scatter(x, y, marker="circle_x", size=sizes, color="#DD1C77", fill_

color=None)

77. figures.append(p)

78. p = figure(title="triangle")

79. p.scatter(x, y, marker="triangle", size=sizes, color="#99D594", line_width=2)

80. figures.append(p)

81. p = figure(title="circle")

82. p.scatter(x, y, marker="o", size=sizes, color="#80B1D3", line_width=3)

83. figures.append(p)

84. p = figure(title="cross")

85. p.scatter(x, y, marker="cross", size=sizes, color="#E6550D", line_width=2)

86. figures.append(p)

87. p = figure(title="diamond")

88. p.scatter(x, y, marker="diamond", size=sizes, color="#1C9099", line_width=2)

89. figures.append(p)

90. p = figure(title="inverted_triangle")

91. p.scatter(x, y, marker="inverted_triangle", size=sizes, color="#DE2D26")

92. figures.append(p)

93. p = figure(title="square_x")

94. p.scatter(x, y, marker="square_x", size=sizes, color="#FDAE6B",

95. fill_color=None, line_width=2)

96. figures.append(p)

97. p = figure(title="asterisk")

98. p.scatter(x, y, marker="asterisk", size=sizes, color="#F0027F",

99. line_width=2)

100. figures.append(p)

101. p = figure(title="square_cross")

102. p.scatter(x, y, marker="square_cross", size=sizes, color="#7FC97F",

103. fill_color=None, line_width=2)

104. figures.append(p)

105. p = figure(title="diamond_cross")

106. p.scatter(x, y, marker="diamond_cross", size=sizes, color="#386CB0",

107. fill_color=None, line_width=2)

108. figures.append(p)

109. p = figure(title="circle_cross")

110. p.scatter(x, y, marker="circle_cross", size=sizes, color="#FB8072",

111. fill_color=None, line_width=2)

112. figures.append(p)

113. # 网格展示

114. show(gridplot(figures, ncols=4, plot_width=200, plot_height=200))

运行结果如图2-1和图2-2所示。

图2-1　代码示例2-1运行结果(1)

图2-2　代码示例2-1运行结果(2)

代码示例2-1展示了Bokeh figure()类的30种基本图元绘制方法，灵活地使用这些方法，可以绘制出各式各样的复杂图形，其中，有些图形可以用不同的基本图元实现，读者在学习过程中可以做不同的尝试。

代码示例　2-2

1. from bokeh.sampledata.iris import flowers

2. from bokeh.transform import factor_cmap, factor_mark

3. # 鸢尾花品种及分类标记

4. SPECIES = ['setosa', 'versicolor', 'virginica']

5. MARKERS = ['hex', 'circle_x', 'triangle']

6. # 画布

7. p = figure(title = "Iris Morphology", background_fill_color="#fafafa")

8. # 绘图

9. p.scatter("petal_length", "sepal_width", source=flowers, legend="species", fill_alpha=0.4, size=12,

10. marker=factor_mark('species', MARKERS, SPECIES),

11. color=factor_cmap('species', 'Category10_3', SPECIES))

12. # 其他

13. p.xaxis.axis_label = 'Petal Length'

14. p.yaxis.axis_label = 'Sepal Width'

15. # 显示

16. show(p)

运行结果如图2-3所示。

图2-3　代码示例2-2运行结果

代码示例2-2以散点图展示了机器学习中大名鼎鼎的鸢尾花数据集的分类结果。在2.2节中，我们可以看到circle的方法和scatter方法均可以实现散点图的绘制。本节着重了解figure()类的常用基本属性。

figure(**kwargs)常用基本属性。

'plot_height':400(画布高度，默认值400)

'plot_width':400

'renderers':[GlyphRenderer(id='1037',...)](自定义渲染数据)

'x_range':DataRange1d(id='1003',...)(x轴范围)

'x_scale':LinearScale(id='1007',...)(x轴刻度比例)

'y_range':DataRange1d(id='1005',...)(y轴范围)

'y_scale':LinearScale(id='1009',...)(y轴刻度比例)

'title':Title(id='1040',...)(标题)

'toolbar':Toolbar(id='1027',...)(工具栏)

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