Matplotlib庫 標注在工作有很大作用:
Annotate的構造函數為 ：Annotation(s, xy, xytext=None, xycoords=‘data’, textcoords=None, arrowprops=None, annotation_clip=None, **kwargs) 用於繪制連接圖上兩點的箭頭。
關鍵參數：
- s 為注釋文本內容
- xy 為被注釋的坐標點，二維元組形如(x,y)
- xytext 為注釋文本的坐標點，也是二維元組，默認與xy相同
- xycoords為被注釋點的坐標系屬性(通常xycoords值為’data’，即以被注釋的坐標點xy為參考)
-
Value Description
================= =============================================
'figure points' Points from the lower left of the figure
'figure pixels' Pixels from the lower left of the figure
'figure fraction' Fraction of figure from lower left
'axes points' Points from lower left corner of axes
'axes pixels' Pixels from lower left corner of axes
'axes fraction' Fraction of axes from lower left
'data' Use the coordinate system of the object being
annotated (default)
'polar' *(theta, r)* if not native 'data' coordinates
================= =============================================
-
- textcoords 設置注釋文本的坐標系屬性(textcoords 選擇為相對於被注釋點xy的偏移量，‘offset points’或者’offset pixels’)
arrowprops為箭頭的樣式，dict（字典）型數據，如果該屬性非空，則會在注釋文本和被注釋點之間畫一個箭頭。如果不設置’arrowstyle’關鍵字，則允許包含關鍵字width、headwidth、headlength、shrink,以下是arrowstyle的可選值
-
Name Attrs
============ =============================================
``'-'`` None
``'->'`` head_length=0.4,head_width=0.2
``'-['`` widthB=1.0,lengthB=0.2,angleB=None
``'|-|'`` widthA=1.0,widthB=1.0
``'-|>'`` head_length=0.4,head_width=0.2
``'<-'`` head_length=0.4,head_width=0.2
``'<->'`` head_length=0.4,head_width=0.2
``'<|-'`` head_length=0.4,head_width=0.2
``'<|-|>'`` head_length=0.4,head_width=0.2
``'fancy'`` head_length=0.4,head_width=0.4,tail_width=0.4
``'simple'`` head_length=0.5,head_width=0.5,tail_width=0.2
``'wedge'`` tail_width=0.3,shrink_factor=0.5
============ =============================================
兩個點之間的連接路徑。 這由connectionstyle鍵值控制。
Angle(angleA=90, angleB=0, rad=0.0)[source] Angle3(angleA=90, angleB=0) Arc(angleA=0, angleB=0, armA=None, armB=None, rad=0.0) Arc3(rad=0.0)[source] Bar(armA=0.0, armB=0.0, fraction=0.3, angle=None)[source]
在
pyplot模塊（或
Axes類的
text方法
get_bbox_patch/set_boxstyle("rarrow", pad=0.6)）中的
text()函數接受
bbox關鍵字參數，並且在提供時，在文本周圍繪制一個框。常用參數如下：
import matplotlib.pyplot as plt import numpy as np import matplotlib.path as mpath import matplotlib.lines as mlines import matplotlib.patches as mpatches from matplotlib.collections import PatchCollection def label(xy, text): y = xy[1] - 0.15 # shift y-value for label so that it's below the artist plt.text(xy[0], y, text, ha="center", family='sans-serif', size=14) fig, ax = plt.subplots() # create 3x3 grid to plot the artists grid = np.mgrid[0.2:0.8:3j, 0.2:0.8:3j].reshape(2, -1).T patches = [] # add a circle circle = mpatches.Circle(grid[0], 0.1, ec="none") patches.append(circle) label(grid[0], "Circle") # add a rectangle rect = mpatches.Rectangle(grid[1] - [0.025, 0.05], 0.05, 0.1, ec="none") patches.append(rect) label(grid[1], "Rectangle") # add a wedge wedge = mpatches.Wedge(grid[2], 0.1, 30, 270, ec="none") patches.append(wedge) label(grid[2], "Wedge") # add a Polygon polygon = mpatches.RegularPolygon(grid[3], 5, 0.1) patches.append(polygon) label(grid[3], "Polygon") # add an ellipse ellipse = mpatches.Ellipse(grid[4], 0.2, 0.1) patches.append(ellipse) label(grid[4], "Ellipse") # add an arrow arrow = mpatches.Arrow(grid[5, 0] - 0.05, grid[5, 1] - 0.05, 0.1, 0.1, width=0.1) patches.append(arrow) label(grid[5], "Arrow") # add a path patch Path = mpath.Path path_data = [ (Path.MOVETO, [0.018, -0.11]), (Path.CURVE4, [-0.031, -0.051]), (Path.CURVE4, [-0.115, 0.073]), (Path.CURVE4, [-0.03, 0.073]), (Path.LINETO, [-0.011, 0.039]), (Path.CURVE4, [0.043, 0.121]), (Path.CURVE4, [0.075, -0.005]), (Path.CURVE4, [0.035, -0.027]), (Path.CLOSEPOLY, [0.018, -0.11])] codes, verts = zip(*path_data) path = mpath.Path(verts + grid[6], codes) patch = mpatches.PathPatch(path) patches.append(patch) label(grid[6], "PathPatch") # add a fancy box fancybox = mpatches.FancyBboxPatch( grid[7] - [0.025, 0.05], 0.05, 0.1, boxstyle=mpatches.BoxStyle("Round", pad=0.02)) patches.append(fancybox) label(grid[7], "FancyBboxPatch") # add a line x, y = np.array([[-0.06, 0.0, 0.1], [0.05, -0.05, 0.05]]) line = mlines.Line2D(x + grid[8, 0], y + grid[8, 1], lw=5., alpha=0.3) label(grid[8], "Line2D") colors = np.linspace(0, 1, len(patches)) collection = PatchCollection(patches, cmap=plt.cm.hsv, alpha=0.3) collection.set_array(np.array(colors)) ax.add_collection(collection) ax.add_line(line) plt.axis('equal') plt.axis('off') plt.tight_layout() plt.show()
- boxstyle方框外形，參數是框樣式的名稱與其作為關鍵字參數的屬性
- facecolor(簡寫fc)背景顏色
- edgecolor(簡寫ec)邊框線條顏色
- edgewidth邊框線條大小
box類 名稱 屬性
Circle circle pad=0.3
DArrow darrow pad=0.3
LArrow larrow pad=0.3
RArrow rarrow pad=0.3
Round round pad=0.3,rounding_size=None
Round4 round4 pad=0.3,rounding_size=None
Roundtooth roundtooth pad=0.3,tooth_size=None
Sawtooth sawtooth pad=0.3,tooth_size=None
Square square pad=0.3
案例
import numpy as np import matplotlib.pylab as plt x = np.arange(0, 10, 0.005) y = np.exp(-x / 2.) * np.sin(2 * np.pi * x) fig = plt.figure() ax = fig.add_subplot(111) ax.plot(x, y) ax.set_xlim(0, 10) ax.set_ylim(-1, 1) xdata, ydata = 5, 0 xdisplay, ydisplay = ax.transData.transform_point((xdata, ydata)) bbox = dict(boxstyle="round", fc="0.8") arrowprops = dict(arrowstyle="<|-|>",connectionstyle="angle,angleA=0,angleB=90,rad=10") offset = 100 ax.annotate('data = (%.1f, %.1f)' % (xdata, ydata), xy=(xdata, ydata), xytext=(1 * offset, offset), textcoords='offset pixels', bbox=bbox, arrowprops=arrowprops) disp = ax.annotate('display = (%.1f, %.1f)' % (xdisplay, ydisplay), (xdisplay, ydisplay), xytext=(0.5 * offset, -offset), xycoords='figure pixels', textcoords='offset points', bbox=bbox, arrowprops=arrowprops) plt.show()
