1

我创建了一些代码：

 import numpy as np
 Length=(2.7)*10**-3
 Nx=4
 x = np.linspace(0, Length, Nx+1)   # mesh points in space
 t1=110
 t2=100
 m=((t2-t1)/Length)
 T=5
 N=5        
 t = np.linspace(0, T, N+1)
 Coeff=0.5
 b=0.2
 tamb = 20
 u = np.zeros(Nx+1)
 u_1 = np.zeros(Nx+1)
 for i in range(0, Nx+1):
   u_1[i] = m*(x[i])+t1
 #print u_1
 r=[]
 for n in range(0, N+1):
 # Compute u at inner mesh points
 for i in range(0,1):
    u[i] = 2*Coeff*(u_1[i+1]+b*tamb)+(1-2*Coeff-2*b*Coeff)*u_1[i]
 for i in range(1,Nx):
    u[i] = Coeff*(u_1[i+1]+u_1[i-1])+(1-2*Coeff)*u_1[i]
 for i in range(Nx,Nx+1):
    u[i] = 2*Coeff*(u_1[i-1])+(1-2*Coeff)*u_1[i]
 # Switch variables before next step
 u_1, u = u, u_1
 r.append(u.copy()) 
 print r[5]

代码输出：

 [  78.1562   94.1595   96.82    102.6375  102.125 ]

使用我创建了一个应用于数组的函数的代码：

def function(data,time):
  import numpy as np
  Values=data[n]
  Length=(Values[2])*10**-3
  Nx=4
  x = np.linspace(0, Length, Nx+1)   # mesh points in space
  t1=Values[0]
  t2=Values[1]
  m=((t2-t1)/Length)
  T=time[5]
  N=5        
  t = np.linspace(0, T, N+1)
  Coeff=0.5
  b=0.2
  tamb = 20
  u = np.zeros(Nx+1)
  u_1 = np.zeros(Nx+1)
  for i in range(0, Nx+1):
      u_1[i] = m*(x[i])+t1
    #print u_1
  r=[]
  for n in range(0, N+1):
  # Compute u at inner mesh points
      for i in range(0,1):
        u[i] = 2*Coeff*(u_1[i+1]+b*tamb)+(1-2*Coeff-2*b*Coeff)*u_1[i]
      for i in range(1,Nx):
        u[i] = Coeff*(u_1[i+1]+u_1[i-1])+(1-2*Coeff)*u_1[i]
      for i in range(Nx,Nx+1):
        u[i] = 2*Coeff*(u_1[i-1])+(1-2*Coeff)*u_1[i]
  # Switch variables before next step
      u_1, u = u, u_1
      r.append(u.copy()) 
  return r
import numpy as np

#arrays
data=np.array(((110,100,2.5),(112,105,2.6),(115,109,2.7)))
time=np.array((0,1,2,3,4,5))
#apply function to array
for n in range(len(data)):
   r = function(data,time)
   print r[5]

第一个代码工作正常，但是当我使用函数（第二个代码）应用代码时，如果我告诉我得到以下错误：

Traceback (most recent call last):
File "C:/Users/a/Desktop/functiontrial3.py", line 39, in <module>
r = function(data,time)
File "C:/Users/a/Desktop/functiontrial3.py", line 3, in function
Values=data[n]
UnboundLocalError: local variable 'n' referenced before assignment

我必须做什么才能使以下代码正常工作？

4

3 回答 3

3

你在n这里使用全局

Values=data[n]

您在n这里用作局部变量

for n in range(0, N+1):

Python 不允许您n在同一范围内同时用作全局和本地。

它应该是相同n的还是只是对变量名的错误重用？

有几种方法可以修复此错误，但这取决于您的意图。

于 2013-06-03T00:37:41.027 回答
1

更改您的函数签名：

def function(data,time,n):

并这样称呼它：

for n in xrange(len(data)):
   r = function(data,time,n)
于 2013-06-02T23:53:10.567 回答
0

您正在尝试在循环块本地的定义函数中使用变量 n for n in range(0, N+1): ，因为函数头def function(data,time):不包含任何引用 n 的参数参数，所以代码没有到达 n 获取值的点它不是全局的（因此，它变得未定义/未绑定）。根据您希望如何解决问题，您应该将变量设置到位，以便它可以例如执行。

def function(data, time, n):#n passed as positional argument
    Values=data[n]
    --snip--

或者

def function(data, time, n):#n passed as positional argument
    for n in range(0, N+1): 
        # Compute u at inner mesh points
        # As per your problem, the rest will depend on you target...
        Values=data[n]
        --snip--
于 2019-05-02T00:47:56.910 回答