在您的代码中的最后一个示例中,您可以使用headwidth
,frac
并width
自定义箭头,结果arrow0
如下所示。对于高度自定义的箭头,您可以使用任意多边形。下面你可以看到我用来生成数字的代码。
要添加更多多边形,您必须编辑polygons
字典,并且新多边形的第一个和最后一个点必须在原点(0,0)
,重新缩放和重新定位是自动完成的。下图说明了多边形是如何定义的。
收缩仍然存在将线与多边形断开的问题。使用此自定义可以轻松创建您请求的“|-|>”箭头。
代码如下:
import matplotlib.pyplot as plt
import matplotlib.patches as patches
from matplotlib import transforms
import numpy as np
from numpy import cos, sin
plt.close()
plt.plot([1,2],[0,4], 'w')
ax = plt.gcf().axes[0]
def patchesAB(styleA, styleB, orig, target,
widthA, lengthA, widthB, lengthB,
kwargsA, kwargsB, shrinkA=0., shrinkB=0.):
'''
Select 'styleA' and 'styleB' from the dictionary 'polygons'
widthA, lengthA, widthB, lenghtB, shrinkA, shrinkB are defined in points
kwargsA and kwargsB are dictionaries
'''
polygons = {\
'|':np.array([[0,0],[0,1],[0.1,1],[0.1,-1],[0,-1],[0,0]], dtype=float),
'arrow1':np.array([[0,0],[0,1],[-1,2],[3,0],[-1,-2],[0,-1],[0,0]], dtype=float),
'arrow2':np.array([[0,0],[-1,1],[0,2],[3,0],[0,-2],[-1,-1],[0,0]], dtype=float),
}
xyA = polygons.get( styleA )
xyB = polygons.get( styleB )
#
fig = plt.gcf()
ax = fig.axes[0]
trans = ax.transData
pixPunit = trans.transform([(1,0),(0,1)])-ax.transData.transform((0,0))
unitPpix = pixPunit
unitPpix[0,0] = 1/unitPpix[0,0]
unitPpix[1,1] = 1/unitPpix[1,1]
#
orig = np.array(orig)
target = np.array(target)
vec = target-orig
angle = np.arctan2( vec[1], vec[0] )
#
lengthA *= unitPpix[0,0]
lengthB *= unitPpix[0,0]
widthA *= unitPpix[1,1]
widthB *= unitPpix[1,1]
orig += (unitPpix[1,1]*sin(angle)+unitPpix[0,0]*cos(angle))*vec*shrinkA
target -= (unitPpix[1,1]*sin(angle)+unitPpix[0,0]*cos(angle))*vec*shrinkB
#TODO improve shrinking... another attempt:
#orig += unitPpix.dot(vec) * shrinkA
#target -= unitPpix.dot(vec) * shrinkB
# polA
if xyA != None:
a = transforms.Affine2D()
tA = a.rotate_around( orig[0], orig[1], angle+np.pi ) + trans
xyA = np.float_(xyA)
xyA[:,0] *= lengthA/(xyA[:,0].max()-xyA[:,0].min())
xyA[:,1] *= widthA/(xyA[:,1].max()-xyA[:,1].min())
xyA += orig
polA = patches.Polygon( xyA, **kwargsA )
polA.set_transform( tA )
else:
polA = None
# polB
if xyB != None:
a = transforms.Affine2D()
tB = a.rotate_around( target[0], target[1], angle ) + trans
xyB = np.float_(xyB)
xyB[:,0] *= lengthB/(xyB[:,0].max()-xyB[:,0].min())
xyB[:,1] *= widthB/(xyB[:,1].max()-xyB[:,1].min())
xyB += target
polB = patches.Polygon( xyB, **kwargsB )
polB.set_transform( tB )
else:
polB = None
return polA, polB
# ARROW 0
plt.annotate('arrow0',xy=(2,1.5),xycoords='data',
xytext=(1.1,1), textcoords='data',
arrowprops=dict(frac=0.1,headwidth=10., width=2.))
#
kwargsA = dict( lw=1., ec='k', fc='gray' )
kwargsB = dict( lw=1., ec='k', fc='b' )
# ARROW 1
orig = (1.1,2.)
target = (2.,2.5)
shrinkA = 0.
shrinkB = 0.
polA, polB = patchesAB( '|', 'arrow1', orig, target, 20.,1.,60.,60.,
kwargsA, kwargsB, shrinkA, shrinkB )
ax.add_patch(polA)
ax.add_patch(polB)
ax.annotate('arrow1', xy=target, xycoords='data',
xytext=orig, textcoords='data',
arrowprops=dict(arrowstyle='-', patchA=polA, patchB=polB,
lw=1., shrinkA=shrinkA, shrinkB=shrinkB, relpos=(0.,0.),
mutation_scale=1.))
# ARROW 2
orig = (1.1,3.)
target = (2.,3.5)
polA, polB = patchesAB( '|', 'arrow2', orig, target, 20.,1.,60.,60.,
kwargsA, kwargsB, shrinkA, shrinkB )
ax.add_patch(polA)
ax.add_patch(polB)
ax.annotate('arrow2', xy=target, xycoords='data',
xytext=orig, textcoords='data',
arrowprops=dict(arrowstyle='-', patchA=polA, patchB=polB,
lw=1., shrinkA=shrinkA, shrinkB=shrinkB, relpos=(0.,0.),
mutation_scale=1.))
plt.autoscale()
plt.xlim(1.,2.2)
plt.ylim(0.5,4)
plt.show()