Python Numpy Addition

Question

I have an array like this:

array = [([476301.98163511883, 6176897.129456658],)
     ([476723.365551495, 6176895.078376785],)
     ([477124.59457628336, 6176893.28525448],)
     ([477525.82249430567, 6176891.306532074],)
     ([477927.0510582989, 6176889.4760845825],)
     ([477925.0121537624, 6176487.379134962],)
     ([477922.97333802003, 6176085.2824224755])]

All I'm trying to do is add 5 to the first number and 10 to the second. I tried this

for x in numpy.nditer(array, op_flags=['readwrite']):
    x + numpy.array([5, 10])

Which gives TypeError: unsupported operand type(s) for +: 'numpy.ndarray' and 'numpy.ndarray'

Yet something like this works fine

b = numpy.array([0, 10])
x = numpy.array([10, 10])
c = x + b

@Aaron Hall It's how my data comes in. I don't really have any control over it. Guessing this is the root of my problem. — Tristan Forward
– Tristan Forward, Commented Dec 3, 2014 at 4:38

Aaron Hall · Accepted Answer · 2014-12-03 04:46:47Z

1

After adjusting your data by the removing the extra parentheses (which were missing commas, and so would not be legal Python) so that it's a 7 by 2 array, I then add it to an array of 5, 10:

import numpy as np
array = np.array([[476301.98163511883, 6176897.129456658],
     [476723.365551495, 6176895.078376785],
     [477124.59457628336, 6176893.28525448],
     [477525.82249430567, 6176891.306532074],
     [477927.0510582989, 6176889.4760845825],
     [477925.0121537624, 6176487.379134962],
     [477922.97333802003, 6176085.2824224755]])

and now:

>>> array
array([[  476301.98163512,  6176897.12945666],
       [  476723.36555149,  6176895.07837678],
       [  477124.59457628,  6176893.28525448],
       [  477525.82249431,  6176891.30653207],
       [  477927.0510583 ,  6176889.47608458],
       [  477925.01215376,  6176487.37913496],
       [  477922.97333802,  6176085.28242248]])
>>> array + np.array([5, 10])
array([[  476306.98163512,  6176907.12945666],
       [  476728.36555149,  6176905.07837678],
       [  477129.59457628,  6176903.28525448],
       [  477530.82249431,  6176901.30653207],
       [  477932.0510583 ,  6176899.47608458],
       [  477930.01215376,  6176497.37913496],
       [  477927.97333802,  6176095.28242248]])

Array addition will be much faster than iteratively adding the elements together.

edited Dec 3, 2014 at 4:46

answered Dec 3, 2014 at 4:41

Aaron Hall♦

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4 Comments

Tristan Forward Over a year ago

Thanks. How do I adjusting the data so that it's a 7 by 2 array? The extra parens are causing problems.

Aaron Hall Over a year ago

Delete them, that's what I did. It's not legal python.

Tristan Forward Over a year ago

It's how my data comes in. I have limited control on the output, I can make it look like this: [(476301.98163511883, 6176897.129456658) (476723.365551495, 6176895.078376785) (477124.59457628336, 6176893.28525448)] but I still run into the same problem

Aaron Hall Over a year ago

put commas between the parentheses groups, and then you can pass it to np.array.

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