通过相同的方程式处理不同的数据

Question

I have an array that looks like this:

A=[  id.                 r            d    ]
[[  47.          223.25190261   58.0551391 ]
 [  49.          223.25102751   58.05662719]
 [  57.          223.25013049   58.05139459]]

The first column isnt important. The following two are though, they are coordinates.

I have to compare EACH set of coordinates (column 2 and 3 together) against these coordinates: (223.251, 58.05) by using this equation: B=sin(D)sin(d) + cos(D)cos(d)cos(Rr).

Where (R,D) are the original coordinates (223.251, 58.05) and (r,d) are the coordinates in the array. How do I do this for each set of coordinates in the array without having to input the numbers myself or having to define each number and replace them with the next set of coordinates? I want the program to obviously keep (R,D) consistent and change (r,d) for each row and make the calculations. After it's done making the calculation for each row I want to have them output. I really have no idea how to do this, I'm thinking maybe something with a loop. I'm seriously lost. The end of the code is this:

B=(((sin(dec0))*(sin(dec1)) + (cos(dec0)*cos(dec1))*(cos(ra0-ra1))))
print B
0.540302302454

But this only does the first row of coordinates, I want it to be done manually

Answer 1

I'm not sure if the formula is correct and data representative, because your values are really close to each other. Anyway, to print the B value for each item in your data, you can use:

from math import radians, sin, cos

orig = (223.251, 58.05)
R = radians(orig[0])
D = radians(orig[1])

A = [[  47.,  223.25190261,   58.0551391 ],
     [  49.,  223.25102751,   58.05662719],
     [  57.,  223.25013049,   58.05139459]]

for item in A:
  r = radians(item[1])
  d = radians(item[2])
  B = sin(D)*sin(d) + cos(D)*cos(d)*cos(R-r)
  print(B)

if you've got numpy array as input, use numpy module instead of math of course.

Answer 2

If you are willing to use NumPy you the operations can be vectorized avoiding the for loops like:

from numpy import array, deg2rad, sin, cos

orig = (223.251, 58.05)
R = deg2rad(orig[0])
D = deg2rad(orig[1])

A = array([[47., 223.25190261, 58.0551391 ],
           [49., 223.25102751, 58.05662719],
           [57., 223.25013049, 58.05139459]])

r = deg2rad(A[:,1])
d = deg2rad(A[:,2])
B = sin(D)*sin(d) + cos(D)*cos(d)*cos(R-r)

where B is a numpy.ndarray containing the result for each line of A .