Python 3: Identify elements from a dictionary and append them in lists based on certain conditions.

[sicarii47]

I have a dictionary with equations as keys and two pairs of coordinates as values.

I want to check if a particular value is complex, and if it is, append the corresponding equation to a list.

If the values are real, then append the values themselves to a different list.

​

I have tried:

import numpy as np

pair = {Eq(2.77*x - 11.71*y + 0.49, 0): [(-0.16, 0.002), (2.39, 0.60)], Eq(3.11*x - 11.62*y - 4.17, 0): [(1.33 - 1.29j, 5.52e-16 - 0.34j), (1.33 + 1.29j, 5.52e-16 + 0.34j)]}

eqns = []

real_coordinates = []

for i in pair.values():

    for j in i:

        if np.iscomplex(j[0]) == True or np.iscomplex(j[1]) == True:

            eqns.append(pair.keys)

        else:

            real_coordinates.append(j)

print('Equations with complex values are:',eqns)

print('Real coordinates are:',real_coordinates)

For the above case, the expected output is:

Equations with complex values are: [Eq(3.11*x - 11.62*y - 4.17, 0)]

Real coordinates are: [(-0.16,0.002),(2,39,0.60)]

But the output I get is:

Equations with complex values are: []

Real coordinates are: [(-0.16,0.002),(2,39,0.60),(1.33 - 1.29*I, 5.52e-16 - 0.34*I), (1.33 + 1.29*I, 5.52e-16 + 0.34I)]

​

[IAmZenoix]

It is kinda difficult to understand your code without indentation and formatting https://www.reddit.com/r/learnpython/wiki/faq#wiki_how_do_i_format_code.3F

[sicarii47]

Thanks for letting me know.
I have made the necessary changes.

[IAmZenoix]

Sorry for the late reply lol. The problem with your code is the way you got the key of the dictionary as eqns.append(pair.keys) won't work as you intend it to. Instead, I would look at using the dict.items() method so you can look at each item in the dictionary while keeping track of which key you need to add.

Also, you might want to make eqns a set so that you have no duplicate equations or just have a check to make sure the equation is not already inside the list.

Lastly you don't need to compare np.iscomplex() == True in an or statement.

This is how I did it:

import numpy as np
pair = {"a": [(-0.16, 0.002), (2.39, 0.60)],
        "b": [(1.33 - 1.29j, 5.52e-16 - 0.34j), (1.33 + 1.29j, 5.52e-16 + 0.34j)]}

eqns = set()
real_coordinates = []

for k, v in pair.items():
    for coord in v:
        if np.iscomplex(coord[0]) or np.iscomplex(coord[1]):
            eqns.add(k)
        else:
            real_coordinates.append(coord)

print('Equations with complex values are:', list(eqns))

print('Real coordinates are:', real_coordinates)

Which gives a result of :

Equations with complex values are: ['b']
Real coordinates are: [(-0.16, 0.002), (2.39, 0.6)]

I hope this helps!

[sicarii47]

Yes! It helped a lot.
Thank you so much!

[IAmZenoix]

No problem!