extend the readme (#81)

* add more to the readme

* fix a link

* move the code style after the link to the docs

* move the code style between pypi and conda-forge badge

* use the readme as long description (to be used on PyPI)

* require at least python 3.7

* don't duplicate the long description

* see if upgrading works [skip-ci]

Author: keewis

.github/workflows/ci-additional.yml

@@ -29,7 +29,7 @@ jobs:
           ${{ runner.os }}-pip-py3.8-
     - name: upgrade pip
       run: |
-        python -m pip install --upgrade pip
+        python -m pip install --upgrade pip setuptools wheel
     - name: install dependencies
       run: |
         python -m pip install -r ci/requirements.txt

README.md

@@ -1,2 +1,65 @@
+[![CI](https://github.com/xarray-contrib/pint-xarray/workflows/CI/badge.svg?branch=master)](https://github.com/xarray-contrib/pint-xarray/actions?query=branch%3Amaster)
+[![code coverage](https://codecov.io/gh/xarray-contrib/pint-xarray/branch/master/graph/badge.svg)](https://codecov.io/gh/xarray-contrib/pint-xarray)
+[![docs](https://readthedocs.org/projects/pint-xarray/badge/?version=latest)](https://pint-xarray.readthedocs.io)
+[![PyPI version](https://img.shields.io/pypi/v/pint-xarray.svg)](https://pypi.org/project/pint-xarray)
+[![codestyle](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/python/black)
+[![conda-forge](https://img.shields.io/conda/vn/conda-forge/pint-xarray)](https://github.com/conda-forge/pint-xarray-feedstock)
+
 # pint-xarray
-Interface for using pint in xarray, providing convenience accessors, as [envisioned here](https://github.com/hgrecco/pint/issues/849).
+
+A convenience wrapper for using [pint](https://pint.readthedocs.io) with
+[xarray](https://xarray.pydata.org).
+
+## Usage
+
+To convert the variables of a `Dataset` to quantities:
+```python
+In [1]: import pint_xarray
+   ...: import xarray as xr
+
+In [2]: ds = xr.Dataset({"a": ("x", [0, 1, 2]), "b": ("y", [-3, 5, 1], {"units": "m"})})
+   ...: ds
+Out[2]:
+<xarray.Dataset>
+Dimensions:  (x: 3, y: 3)
+Dimensions without coordinates: x, y
+Data variables:
+    a        (x) int64 0 1 2
+    b        (y) int64 -3 5 1
+
+In [3]: q = ds.pint.quantify(a="s")
+   ...: q
+Out[3]:
+<xarray.Dataset>
+Dimensions:  (x: 3, y: 3)
+Dimensions without coordinates: x, y
+Data variables:
+    a        (x) int64 [s] 0 1 2
+    b        (y) int64 [m] -3 5 1
+```
+to convert to different units:
+```python
+In [4]: c = q.pint.to({"a": "ms", "b": "km"})
+   ...: c
+Out[4]:
+<xarray.Dataset>
+Dimensions:  (x: 3, y: 3)
+Dimensions without coordinates: x, y
+Data variables:
+    a        (x) float64 [ms] 0.0 1e+03 2e+03
+    b        (y) float64 [km] -0.003 0.005 0.001
+```
+to convert back to non-quantities:
+```python
+In [5]: d = c.pint.dequantify()
+   ...: d
+Out[5]:
+<xarray.Dataset>
+Dimensions:  (x: 3, y: 3)
+Dimensions without coordinates: x, y
+Data variables:
+    a        (x) float64 0.0 1e+03 2e+03
+    b        (y) float64 -0.003 0.005 0.001
+```
+
+For more, see the [documentation](https://pint-xarray.readthedocs.io)

setup.cfg

@@ -6,24 +6,23 @@ description = Physical units interface to xarray using Pint
 url = https://github.com/xarray-contrib/pint-xarray
 project_urls =
   Documentation=https://pint-xarray.readthedocs.io/en/stable
-long_description_content_type = text/markdown
 long_description = file: README.md
+long_description_content_type = text/markdown
 classifiers =
     Development Status :: 3 - Alpha
     Environment :: Console
     Intended Audience :: Science/Research
     License :: OSI Approved :: Apache Software License
     Operating System :: OS Independent
     Programming Language :: Python
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Topic :: Scientific/Engineering
 
 [options]
 packages = find:
-python_requires = >=3.6
+python_requires = >=3.7
 install_requires =
     numpy >= 1.17
     xarray >= 0.16.1