feat: align_layout()

Author: szhorvat

src/_igraph/igraphmodule.c

@@ -227,6 +227,39 @@ PyObject* igraphmodule_set_status_handler(PyObject* self, PyObject* o) {
   Py_RETURN_NONE;
 }
 
+PyObject* igraphmodule_align_layout(PyObject* self, PyObject* args, PyObject* kwds) {
+  static char* kwlist[] = {"graph", "layout", NULL};
+  PyObject *pygraph, *pylayout;
+  PyObject *res;
+  const igraph_t *graph;
+  igraph_matrix_t layout;
+
+  if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO", kwlist, &PyList_Type, &pygraph, &pylayout)) {
+    return NULL;
+  }
+
+  graph = PyIGraph_ToCGraph(pygraph);
+  if (graph == NULL) {
+    return NULL;
+  }
+
+  if (! igraphmodule_PyObject_to_matrix_t(pylayout, &layout, "layout")) {
+    return NULL;
+  }
+
+  if (! igraph_layout_align(graph, &layout)) {
+    igraphmodule_handle_igraph_error();
+    igraph_matrix_destroy(&layout);
+    return NULL;
+  }
+
+  res = igraphmodule_matrix_t_to_PyList(&layout, IGRAPHMODULE_TYPE_FLOAT);
+
+  igraph_matrix_destroy(&layout);
+
+  return res;
+}
+
 PyObject* igraphmodule_convex_hull(PyObject* self, PyObject* args, PyObject* kwds) {
   static char* kwlist[] = {"vs", "coords", NULL};
   PyObject *vs, *o, *o1 = 0, *o2 = 0, *o1_float, *o2_float, *coords = Py_False;
@@ -790,6 +823,14 @@ static PyMethodDef igraphmodule_methods[] =
     METH_VARARGS | METH_KEYWORDS,
     "_power_law_fit(data, xmin=-1, force_continuous=False, p_precision=0.01)\n--\n\n"
   },
+  {"align_layout", (PyCFunction)igraphmodule_align_layout,
+    METH_VARARGS | METH_KEYWORDS,
+    "align_layout(graph, layout)\n--\n\n"
+    "Align a graph layout with the coordinate axes.\n\n"
+    "@param graph: the graph whose layout to align\n"
+    "@param layout: the vertex coordinates\n"
+    "@return: the aligned vertex coordinates."
+  },
   {"convex_hull", (PyCFunction)igraphmodule_convex_hull,
     METH_VARARGS | METH_KEYWORDS,
     "convex_hull(vs, coords=False)\n--\n\n"

src/igraph/__init__.py

@@ -62,6 +62,7 @@
     TREE_UNDIRECTED,
     Vertex,
     WEAK,
+    align_layout,
     arpack_options as default_arpack_options,
     community_to_membership,
     convex_hull,
@@ -1202,6 +1203,7 @@ def write(graph, filename, *args, **kwds):
     "VertexCover",
     "VertexDendrogram",
     "VertexSeq",
+    "align_layout",
     "autocurve",
     "color_name_to_rgb",
     "color_name_to_rgba",