Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Here is an easy solution that requires only scipy:</p> <pre><code>def in_hull(p, hull): """ Test if points in `p` are in `hull` `p` should be a `NxK` coordinates of `N` points in `K` dimensions `hull` is either a scipy.spatial.Delaunay object or the `MxK` array of the coordinates of `M` points in `K`dimensions for which Delaunay triangulation will be computed """ from scipy.spatial import Delaunay if not isinstance(hull,Delaunay): hull = Delaunay(hull) return hull.find_simplex(p)&gt;=0 </code></pre> <p>It returns a boolean array where <code>True</code> values indicate points that lie in the given convex hull. It can be used like this:</p> <pre><code>tested = np.random.rand(20,3) cloud = np.random.rand(50,3) print in_hull(tested,cloud) </code></pre> <p>If you have matplotlib installed, you can also use the following function that calls the first one and plots the results. For 2D data only, given by <code>Nx2</code> arrays:</p> <pre><code>def plot_in_hull(p, hull): """ plot relative to `in_hull` for 2d data """ import matplotlib.pyplot as plt from matplotlib.collections import PolyCollection, LineCollection from scipy.spatial import Delaunay if not isinstance(hull,Delaunay): hull = Delaunay(hull) # plot triangulation poly = PolyCollection(hull.points[hull.vertices], facecolors='w', edgecolors='b') plt.clf() plt.title('in hull') plt.gca().add_collection(poly) plt.plot(hull.points[:,0], hull.points[:,1], 'o', hold=1) # plot the convex hull edges = set() edge_points = [] def add_edge(i, j): """Add a line between the i-th and j-th points, if not in the list already""" if (i, j) in edges or (j, i) in edges: # already added return edges.add( (i, j) ) edge_points.append(hull.points[ [i, j] ]) for ia, ib in hull.convex_hull: add_edge(ia, ib) lines = LineCollection(edge_points, color='g') plt.gca().add_collection(lines) plt.show() # plot tested points `p` - black are inside hull, red outside inside = in_hull(p,hull) plt.plot(p[ inside,0],p[ inside,1],'.k') plt.plot(p[-inside,0],p[-inside,1],'.r') </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POWhat's an efficient way to find if a point lies in the convex hull of a point cloud?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USSildoreth
    1. USJuh_
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COthis answer works in n dimensions!
      singulars
      1. PO
      1. USjoshua
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload