Update install docs (#720)

* Update install docs

Includes instruction for editable Python install.

* Update install instructions

* Close up some lines

---------

Co-authored-by: Matthew Scroggs <matthew.w.scroggs@gmail.com>

INSTALL.md

@@ -3,46 +3,48 @@
 ## Standard
 
 Basix can be installed using
-
 ```console
 pip install .
 ```
 
 ## Advanced
 
-In the standard install, the C++ library is built and installed inside the
-Python package.  This method is suitable for the majority of use cases.
-
 It is also possible to install the C++ and Python interfaces separately
-(see below). This is useful if you only need the C++ interface, and can
-be helpful during development.
+(see below). This is useful if you only need the C++ interface or during
+development.
 
 ### C++ library
 
 In the `cpp/` directory:
-
 ```console
 cmake -DCMAKE_BUILD_TYPE=Release -B build-dir -S .
 cmake --build build-dir
 cmake --install build-dir
 ```
-
-You may need to use `sudo` for the final install step. Using the CMake
-build type `Release` is strongly recommended for performance.
+Using the CMake build type `Release` is strongly recommended for
+performance.
 
 
 ### Python interface
 
-After installing the C++ library, install the Python interface by running in
-the directory `python/`:
-
+After installing the C++ library, install the Python interface by
+running in the directory `python/`:
 ```console
 pip install .
 ```
 
+For an editable build and to avoid pip downloading the build
+dependencies:
+```console
+pip install --no-build-isolation -e .
+```
+When using the `--no-build-isolation` option all build and runtime
+dependencies must already be installed.
+
 ## Running the unit tests
 
-To install Basix and the extra dependencies required to run the Python unit tests:
+To install Basix and the extra dependencies required to run the Python
+unit tests:
 
 ```console
 pip install .[test]
@@ -63,18 +65,12 @@ Basix requires a C++20 compiler and depends on BLAS and LAPACK.
 ### Python
 
 When using the standard install approach all build and runtime
-dependencies for the C++ and Python parts of Basix will be fetched
+dependencies for the C++ and Python parts of Basix are fetched
 automatically.
 
-Building the Python interface requires
-[`nanobind`](https://github.com/wjakob/nanobind).
-
-At runtime Basix requires [`numpy`](https://numpy.org).
-
-Basix specifies sets of optional extras `docs`, `lint`, `optional`, `test`, and
-`ci` for building documentation, linting, enabling optional features, testing
-and for continuous integration, respectively, e.g.:
-
+Basix specifies sets of optional extras `docs`, `lint`, `optional`,
+`test`, and `ci` for building documentation, linting, enabling optional
+features, testing and for continuous integration, respectively, e.g.:
 ```console
 pip install .[docs,lint]
 ```

README.md

@@ -15,8 +15,8 @@ Basix allows users to:
   arbitrary meshes; and
 - interpolate into and between finite element spaces.
 
-Basix includes a range of built-in elements, and also allows the user to define
-their own custom elements.
+Basix includes a range of built-in elements, and also allows the user to
+define their own custom elements.
 
 Basix is one of the components of FEniCSx, alongside
 [UFL](https://github.com/fenics/ufl),
@@ -31,13 +31,8 @@ pip install fenics-basix
 ```
 We currently build binary wheels for Linux and macOS x86-64 architectures.
 
-To install the `main` (development) branch of Basix:
-```console
-pip install git+https://github.com/FEniCS/basix.git
-```
-
-For advanced installation instructions see the detailed [install
-instructions](INSTALL.md)
+For advanced and developer installation instructions see the more
+detailed [install instructions](INSTALL.md)
 
 
 ## Documentation
@@ -47,14 +42,17 @@ https://docs.fenicsproject.org/basix/main/.
 
 ## Support
 
-If you find a bug in Basix, you can report it on the [GitHub issue tracker](https://github.com/fenics/basix/issues/new?labels=bug).
+If you find a bug in Basix, you can report it on the [GitHub issue
+tracker](https://github.com/fenics/basix/issues/new?labels=bug).
 
-Questions about using Basix can be asked on the [FEniCS discourse group](https://fenicsproject.discourse.group/).
+Questions about using Basix can be asked on the [FEniCS discourse
+group](https://fenicsproject.discourse.group/).
 
 
 ## Contributing
 
-Information about how to contribute to Basix can be found [here](CONTRIBUTING.md).
+Information about how to contribute to Basix can be found
+[here](CONTRIBUTING.md).
 
 ## Supported elements
 

python/basix/__init__.py

@@ -3,7 +3,6 @@
 The core of the library is written in C++, but the majority of Basix's
 functionality can be used via this Python interface.
 """
-
 from basix import cell, finite_element, lattice, polynomials, quadrature, sobolev_spaces, variants
 from basix._basixcpp import (CellType, DPCVariant, ElementFamily, LagrangeVariant, LatticeSimplexMethod, LatticeType,
                              MapType, PolynomialType, PolysetType, QuadratureType, SobolevSpace, __version__,