pyorderby

Python key functions for multi-field ordering in SQL ORDER BY fashion

Meant to be used with built-in sorted() key function.

Supports also list.sort() doing in-place sorting.

Usage

• SQL-like: orderby('foo ASC, bar DESC')
• eval like: orderby('$foo - $bar * 10')
• chained: asc('foo').desc('bar') usage
• multiple fields at once: asc('foo', 'bar')

Examples

orderby() string syntax:

>>> from orderby import orderby
>>> import json
>>> files = [
...   {'size': 1234, 'path': 'foo/bar.txt'},
...   {'size': 0, 'path': '/dev/null'},
...   {'size': 1234, 'path': 'foo/abc.bin'},
... ]
>>> print(json.dumps(sorted(files, key=orderby('size DESC, path')), indent=2))
[
  {
    "size": 1234,
    "path": "foo/abc.bin"
  },
  {
    "size": 1234,
    "path": "foo/bar.txt"
  },
  {
    "size": 0,
    "path": "/dev/null"
  }
]

orderby() eval string syntax:

>>> from orderby import orderby
>>> import json
>>> files = [
...   {'size': 1234, 'lines': 2},
...   {'size': 0, 'lines': 100},
...   {'size': 1234, 'lines': 1000},
... ]
>>> print(json.dumps(sorted(files, key=orderby('-$size + $lines')), indent=2))
[
  {
    "size": 1234,
    "lines": 2
  },
  {
    "size": 0,
    "lines": 100
  },
  {
    "size": 1234,
    "lines": 1000
  }
]

Chained asc() and desc() usage:

>>> from orderby import asc, desc
>>> print(json.dumps(sorted(files, key=desc('size').asc('path')), indent=2))
[
  {
    "size": 1234,
    "path": "foo/abc.bin"
  },
  {
    "size": 1234,
    "path": "foo/bar.txt"
  },
  {
    "size": 0,
    "path": "/dev/null"
  }
]

In-place sorting of a list:

>>> files.sort(key=desc('path'))
>>> print(json.dumps(files, indent=2))
[
  {
    "size": 1234,
    "path": "foo/bar.txt"
  },
  {
    "size": 1234,
    "path": "foo/abc.bin"
  },
  {
    "size": 0,
    "path": "/dev/null"
  }
]
>>> files.sort(key=desc('size').asc('path'))
>>> print(json.dumps(files, indent=2))
[
  {
    "size": 1234,
    "path": "foo/abc.bin"
  },
  {
    "size": 1234,
    "path": "foo/bar.txt"
  },
  {
    "size": 0,
    "path": "/dev/null"
  }
]

Works also with SortedContainers:

>>> from sortedcontainers import SortedList
>>> from orderby import desc
>>> mylist = SortedList(key=desc('value'))
>>> mylist
SortedListWithKey([], key=<orderby.sorter.OrderBy object at 0x108f65978>, load=1000)
>>> mylist.add({'value': 13})
>>> mylist.add({'value': 2})
>>> mylist.add({'value': 1000})
>>> mylist
SortedListWithKey([{'value': 1000}, {'value': 13}, {'value': 2}], key=<orderby.sorter.OrderBy object at 0x108f65978>, load=1000)