Hei I am trying to get a plot for the following problem: U (x) =U0, if |x| ≥ x0 U (x)=U0*|x|/x0 if |x| < x0
黑我试图获得一块以下问题:U(x)=情况,如果x | |≥x0 U(x)=情况* | | / x0如果| x | < x0
and programm:
和程序:
from pylab import*
x_0=5
U_0=200
#U_x=zeros(n,1)
#x=zeros(n,1)
x=arange(-20,20,0.01)
if float(abs(x))>=x_0:
U_x=U_0
elif float(abs(x))<x_0:
U_x=U_0*(float(abs(x))/x_0)
fig=figure()
suptitle("a)")
fig.subplots_adjust(hspace=0.5)
plot(x,U_x)
xlabel('x [m]')
ylabel('U_x [J]')
show()
But I always get this mistake:
但我总是犯这样的错误:
if float(abs(x))>=x_0:
TypeError: only length-1 arrays can be converted to Python scalars
Please help:)
请帮助:)
1 个解决方案
#1
8
abs(x) is an array, you can't convert the array to a float value, that is the error. You can write a for loop to do the calculation, but numpy can do vectorized if condition by numpy.where. For more information, read the document:
abs(x)是一个数组，不能将数组转换为浮点值，这就是错误。您可以编写一个for循环来进行计算，但是numpy可以通过numpi .where对条件进行矢量化。要了解更多信息，请阅读文档:
import numpy as np
x = np.arange(-20, 20, 0.01)
x0 = 5
U0 = 200
u = np.where(np.abs(x) >= x0, U0, U0*np.abs(x)/x0)
plot(x, u, lw=3)
output:
输出:
You can also use piecewise function, it can deal with more complicated case.
你也可以使用分段函数，它可以处理更复杂的情况。
#1
8
abs(x) is an array, you can't convert the array to a float value, that is the error. You can write a for loop to do the calculation, but numpy can do vectorized if condition by numpy.where. For more information, read the document:
abs(x)是一个数组，不能将数组转换为浮点值，这就是错误。您可以编写一个for循环来进行计算，但是numpy可以通过numpi .where对条件进行矢量化。要了解更多信息，请阅读文档:
import numpy as np
x = np.arange(-20, 20, 0.01)
x0 = 5
U0 = 200
u = np.where(np.abs(x) >= x0, U0, U0*np.abs(x)/x0)
plot(x, u, lw=3)
output:
输出:
You can also use piecewise function, it can deal with more complicated case.
你也可以使用分段函数，它可以处理更复杂的情况。