Question

I am trying to convert my algorithm into python code. The algorithm is as follows:

For i = 1 To n
                For j = 1 To (m - 1)
                    del1 = C(i - 1, j) - C(i - 1, j - 1)
                    del2 = C(i - 1, j + 1) - C(i - 1, j)
                    If del2 = 0 Then
                        r = 0
                    Else
                        r = del1 / del2
                    End If
Next i 

I tried to convert the above chunk of code step by stop. For del1 I tried to write the python code as follows:

del1 = [[C[i-1,j]-C[i-1,j-1] for j in range(1,(m-1))]for i in range [0,int(n)]]

I get the error TypeError: ‘type’ object is not subscriptable. Can anyone give me starting point on how to convert the above algorithm into python code ?

Edit:

C = [[0 for j in range(0,int(m))]for i in range(0)]
C = [[1 for i in range(0,int(n))]for j in range(0)]  

Thanks.

Jdbaba

Answer 1

should be:

del1 = [[C[i-1,j]-C[i-1,j-1] for j in range(1,(m-1))]for i in range(0,int(n))]

[] -> () on the last range

The above notation will work if C is something like a numpy array that supports multi-dimensional slicing. If C is a list of lists, the following should work:

del1 = [[C[i-1][j]-C[i-1][j-1] for j in range(1,(m-1))]for i in range(0,int(n))]