feat: added write_graph_lgl() and write_graph_ncol()

Author: ntamas

docs/api/io.md

@@ -0,0 +1,5 @@
+# Reading and writing graphs
+
+## `igraph_ctypes.io` module
+
+::: igraph_ctypes.io

docs/api/types.md

@@ -0,0 +1,5 @@
+# Basic data types
+
+## `igraph_ctypes.types` module
+
+::: igraph_ctypes.types

docs/fragments/_include/write_graph_names.txt

@@ -0,0 +1,4 @@
+    names: name of the string vertex attribute that stores the names of the
+        vertices to be written into the output file. A warning will be thrown if
+        the attribute does not exist or is not a string attribute, and the file
+        will contain numeric vertex IDs instead if this is the case.

docs/fragments/_include/write_graph_weights.txt

@@ -0,0 +1,4 @@
+    weights: name of the edge attribute that stores the weights of the edges
+        to be written into the output file. A warning will be thrown if the
+        attribute does not exist or is not a numeric attribute, and all weights
+        will be assumed to be equal to 1 if this is the case.

docs/fragments/igraph_write_graph_edgelist.txt

@@ -1,6 +1,6 @@
 Writes the graph in plain edge list format to an output stream.
 
-THe plain edge list format records the structure of the graph _only_ and the
+The plain edge list format records the structure of the graph _only_ and the
 vertices of the graph will be referred to as numeric vertex IDs instead of
 vertex names.
 

docs/fragments/igraph_write_graph_lgl.txt

@@ -0,0 +1,14 @@
+Writes the graph in the LGL (Large Graph Layout) format to an output stream.
+
+The LGL format can store the structure of a graph with named vertices and
+weighted edges.
+
+Note that the file format does not store whether the graph is directed or not;
+this information has to be supplied when the graph is read back.
+
+Parameters:
+    graph: the graph to write
+{% include '_include/write_graph_outstream.txt' %}
+{% include '_include/write_graph_names.txt' %}
+{% include '_include/write_graph_weights.txt' %}
+    isolates: whether to save isolated vertices to the output

docs/fragments/igraph_write_graph_ncol.txt

@@ -0,0 +1,15 @@
+Writes the graph in the NCOL format to an output stream.
+
+The NCOL format is essentially a two- or three-column named edge list format.
+Each line in the output corresponds to an edge. The first two columns contain
+the names of the source and target vertices of an edge. THe third column
+(if exists) contains the weight of each edge.
+
+Note that the file format does not store whether the graph is directed or not;
+this information has to be supplied when the graph is read back.
+
+Parameters:
+    graph: the graph to write
+{% include '_include/write_graph_outstream.txt' %}
+{% include '_include/write_graph_names.txt' %}
+{% include '_include/write_graph_weights.txt' %}

mkdocs.yml

@@ -5,9 +5,11 @@ nav:
   - Home: index.md
   - Notes: notes.md
   - API reference:
+      - api/types.md
       - api/graph.md
       - api/constructors.md
       - api/paths.md
+      - api/io.md
 
 exclude_docs: |
   fragments/

src/codegen/internal_lib.py.in

@@ -42,6 +42,7 @@ from .types import (
     igraph_plfit_result_t,
     igraph_rng_t,
     igraph_rng_type_t,
+    igraph_warning_handler_t,
 )
 
 
@@ -556,5 +557,9 @@ igraph_set_interruption_handler = _lib.igraph_set_interruption_handler
 igraph_set_interruption_handler.restype = igraph_interruption_handler_t
 igraph_set_interruption_handler.argtypes = [igraph_interruption_handler_t]
 
+igraph_set_warning_handler = _lib.igraph_set_warning_handler
+igraph_set_warning_handler.restype = igraph_warning_handler_t
+igraph_set_warning_handler.argtypes = [igraph_warning_handler_t]
+
 # The rest of this file is generated by Stimulus
 

src/codegen/run.py

@@ -325,6 +325,7 @@ def main():
             "BoolArray",
             "EdgeLike",
             "EdgeSelector",
+            "FileLike",
             "IntArray",
             "RealArray",
             "VertexLike",