add `templates.python-data`

for more info, see
<https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake-init.html>

flake.nix

@@ -116,6 +116,16 @@
       x86_64-linux = allPkgsFor "x86_64-linux";
       aarch64-linux = allPkgsFor "aarch64-linux";
     };
+    templates = {
+      python-data = {
+        # initialize with:
+        # - `nix flake init -t '/home/colin/dev/nixos/#python-data'`
+        # then enter with:
+        # - `nix develop`
+        path = ./templates/python-data;
+        description = "python environment for data processing";
+      };
+    };
   };
 }
 

templates/python-data/flake.nix

@@ -0,0 +1,23 @@
+{
+  inputs.nixpkgs.url = "nixpkgs/nixpkgs-unstable";
+  inputs.flake-utils.url = github:numtide/flake-utils;
+
+  outputs = { self, nixpkgs, flake-utils }:
+    with flake-utils.lib;
+  eachSystem allSystems (system:
+    let
+      pkgs = import nixpkgs { inherit system; };
+      python-packages = pypkg: with pypkg; [
+        natsort
+        pandas
+        plotly
+        scipy
+      ];
+      python3 = pkgs.python3.withPackages python-packages;
+    in {
+      devShells.default = with pkgs; mkShell {
+        packages = [ python3 ];
+      };
+    }
+  );
+}