Making a 3D scatterplot that changes colors depending on value of Z

Question

I want to make a simple loop that makes a 3D scatterplot. but, i want two colors, depending on value of z in my data.

I know i am doing something wrong with my loop, but can anyone tell me what is wrong?

My code looks like this

import matplotlib.pyplot as plt
import numpy as np

data = np.loadtxt('Koordinater/Co_sektions.txt')
z = data[:,2]
fig = plt.figure(figsize=(10,7))
ax = plt.axes(projection = "3d")
ax.set_zlim(0, 27000)

d1 = range(0,len(data),1)

for i in d1:
    if z[i] <= 1000:
        ax.scatter3D(data[:,1], data[:,0], data[:,2],color='red')
    else:
        ax.scatter3D(data[:,1], data[:,0], data[:,2])
plt.show()

My data looks like

     0  -14450       0
  1583  -14450     902
  1583   14450     902
     0   14450       0
  3166   14450    1704
  3166  -14450    1704
  4749  -14450    2414
  4749   14450    2414
  6332  -14450    3036
  6332   14450    3036
  7915   14450    3576

Answer 1

You could have split the lists into 2 lists, but this is better:

i have not used your data (created my own for simplicity), but you can do something like this:

import matplotlib.pyplot as plt


fig = plt.figure()
ax = fig.add_subplot(projection='3d')
import numpy as np


x = np.array([1,2,3,4,5])
y = np.array([10,20,30,40,50])
z = np.array([100,200,300,400,500])

c = 250 # a threshold criteria
ax.scatter(x[z>c], y[z>c], z[z>c], s=100, c='r', marker='o')
ax.scatter(x[z<=c], y[z<=c], z[z<=c], s=100, c='b', marker='x')

ax.set_xlabel('X Label')
ax.set_ylabel('Y Label')
ax.set_zlabel('Z Label')


plt.show()

which gives this: