changed color name in cm to a static const char

Signed-off-by: soblin <hilo.soblin@gmail.com>

gallery/images_contours_and_fields/contourf_log.cpp

@@ -52,7 +52,7 @@ int main() {
   auto [fig, ax] = plt.subplots();
   auto cs = ax.contourf(Args(Xpy, Ypy, zpy),
                         Kwargs("locator"_a = ticker::LogLocator().unwrap(),
-                               "cmap"_a = cm::PuBu_r()));
+                               "cmap"_a = cm::PuBu_r));
   fig.colorbar(Args(cs));
   plt.show();
 }

gallery/images_contours_and_fields/image_demo.cpp

@@ -2,6 +2,7 @@
 // https://matplotlib.org/stable/gallery/images_contours_and_fields/image_demo.html
 
 #include <matplotlibcpp17/pyplot.h>
+#include <matplotlibcpp17/cm.h>
 
 #include <xtensor/xbuilder.hpp>
 #include <xtensor/xview.hpp>
@@ -43,7 +44,7 @@ int main() {
                vmin = *min_element(Z_.begin(), Z_.end());
   auto Zpy = py::array(py::cast(std::move(Z2D)));
   ax.imshow(Args(Zpy), Kwargs("interpolation"_a = "bilinear",
-                              "cmap"_a = "RdYlGn", "origin"_a = "lower",
+                              "cmap"_a = cm::RdYlGn, "origin"_a = "lower",
                               "extent"_a = py::make_tuple(-3, 3, -3, 3),
                               "vmax"_a = vmax, "vmin"_a = vmin));
 #if USE_GUI

include/matplotlibcpp17/cm.h

@@ -16,11 +16,8 @@ pybind11::object coolwarm() {
   return ret;
 }
 
-pybind11::object PuBu_r() {
-  pybind11::object ret =
-      pybind11::module::import("matplotlib.cm").attr("PuBu_r");
-  return ret;
-}
+static const char *PuBu_r = "PuBu_r";
+static const char *RdYlGn = "RdYlGn";
 
 } // namespace matplotlibcpp17::cm