Add the path of Matplotlib to the link search (for Anaconda)

.github/workflows/rust.yml

@@ -63,6 +63,11 @@ jobs:
     - name: Install Matplotlib (Anaconda)
       if: startsWith(matrix.build, 'Anaconda')
       run: $CONDA/bin/conda install conda-forge::matplotlib
+    - name: Test Matplotlib
+      run: |
+        $CONDA/bin/conda info --base
+        $CONDA/bin/conda info --envs
+        python3 -c "import matplotlib; print(matplotlib.__file__)"
     - name: Install Rust (rustup)
       run: rustup update ${{ matrix.rust }} --no-self-update && rustup default ${{ matrix.rust }}
       shell: bash

build.rs

@@ -0,0 +1,21 @@
+use std::{
+    path::Path,
+    process::Command,
+};
+
+fn main() {
+    let matplotlib = "import matplotlib; print(matplotlib.__file__)";
+    let plt_init = Command::new("python3").args(["-c", matplotlib]).output()
+        .map(|o| o.stdout)
+        .or_else(|_| {
+            Command::new("python").args(["-c", matplotlib]).output()
+                .map(|o| o.stdout)
+        })
+        .expect("Pyhon or package matplotlib not found");
+    let plt_path = String::from_utf8_lossy(&plt_init);
+    let plt_path = Path::new(plt_path.as_ref());
+    if let Some(d) = plt_path.parent() {
+        let d = d.to_str().unwrap();
+        println!("cargo:rustc-env=MATPLOTLIB_DIR={d}");
+    }
+}

src/lib.rs

@@ -18,7 +18,7 @@ use pyo3::{
     prelude::*,
     intern,
     exceptions::{PyFileNotFoundError, PyPermissionError},
-    types::{PyDict, PyList},
+    types::{PyDict, PyList, PyString},
 };
 use numpy::{
     PyArray1,
@@ -102,10 +102,28 @@ If you use Anaconda, see https://github.com/PyO3/pyo3/issues/1554"),
 
 impl std::error::Error for Error {}
 
+/// Import the module `name`.  Try to update the Python search path if
+/// it fails.
+fn pyimport<N>(py: Python<'_>, name: N) -> Result<Py<PyModule>, PyErr>
+where N: IntoPy<Py<PyString>> + Clone {
+    println!("---------------------{:?}", option_env!("MATPLOTLIB_DIR"));
+    match PyModule::import(py, name.clone()) {
+        Ok(m) => Ok(m.into()),
+        Err(e) => {
+            if let Some(d) = option_env!("MATPLOTLIB_DIR") {
+                py.import("sys")?.getattr("path")?
+                    .call_method1("append", (d,)).unwrap();
+                PyModule::import(py, name).map(|m| m.into())
+            } else {
+                Err(e)
+            }
+        }
+    }
+}
+
 /// Import and return a handle to the module `$m`.
 macro_rules! pyimport { ($m: literal) => {
-    Python::with_gil(|py|
-        PyModule::import(py, intern!(py, $m)).map(|m| m.into()))
+    Python::with_gil(|py| pyimport(py, intern!(py, $m)))
 }}
 
 lazy_static! {