问题描述
我想在程序中调用一个函数,它具有与以下相同的格式,但其中 x
值采用形状数组 = (426,240)
的形式。有人可以帮忙吗?
功能是:
def f(x):
if x < 0:
return -2*x
else :
return -x
x = np.arange(-100,100,1)
plt.plot(x,list(map(f,x)),'b-') # for python3
#plt.show()
def nucleation_and_motion_in_G_gradient_fluid_2D(writer,args,R=60):
dx = 2*R / args.height
x = (np.arange(args.width) - args.width // 2) * dx
y = (np.arange(args.height) - args.height // 2) * dx
x,y = np.meshgrid(x,y,indexing='ij')
def source_G(t):
center = np.exp(-0.5*(t-5)**2) * 10
gradient = (1+np.tanh(t-30)) * 0.0003
piecewise_1 = f(x) # ***function f(x) called here***
return -(
np.exp(-0.5*(x*x + y*y)) #+ np.exp(-0.5*((x)**2 + y*y))
) * center + piecewise_1 * gradient # piecewise function test
我已经知道代码适用于 trapezoid
函数与 x
数组的组合,如下所示:
(代码需要:from scipy import signal
)
def trapezoid_signal(x,width=2.,slope=1.,amp=10.,offs=1):
a = slope * width * signal.sawtooth(2 * np.pi * 1/10 * x/width - 0.8,width=0.5)/4.
a[a>amp/2.] = amp/2.
a[a<-amp/2.] = -amp/2.
return a + amp/2. + offs
def source_G(t):
center = np.exp(-0.5*(t-5)**2) * 10
gradient = (1+np.tanh(t-30)) * 0.0003
trapezoid = trapezoid_signal(x,width=40,slope=5,amp=50)
return -(
np.exp(-0.5*(x**2 + y**2))
) * center + trapezoid * gradient # one soliton particle in 2 dimensions of xy with z axis as concentration potential
解决方法
如果你想做这个
def f(x):
if x < 0:
return -2*x
else :
return -x
与矢量化兼容,您可以使用以下(非常常见的)技巧:
def f(x):
neg = x < 0
return neg * (-2 * x) + (1 - neg) * -x
有效!
>>> f(np.arange(-5,5))
array([10,8,6,4,2,-1,-2,-3,-4])