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tabular data querying and pivoting in Python3 (with examples particular to linguistic morphology)
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README.md

QMORPH

QMORPH is a Python3 library for querying and pivoting tabular data. It was first written a number of years ago as part of my doctoral work on Ancient Greek morphology but has potentially broader applications. I've recently updated it to Python 3 and will likely change some things inspired by the Django ORM's query syntax.

Example

from qmorph import *

greek_forms = Rel()
greek_forms.load_cols("forms.txt", ("form", "pos", "parse", "lemma"))

greek_forms.query(PartCount(lambda t: t["pos"]))

Rel initializes the relation.

load_cols parses a given line-per-record, whitespace-delimited file into dictionaries with the given fields.

query then runs the given query or list of queries on those dictionaries.

PartCount is a provided query class that partitions and counts the dictionaries based on the given property function. Above the property function is provided inline but the equivalent could be achieved using the higher-order FIELD function provided:

from qmorph import *

greek_forms = Rel()
greek_forms.load_cols("forms.txt", ("form", "pos", "parse", "lemma"))
greek_forms.query(PartCount(FIELD("pos")))

which is equivalent to our first example.

Often you end up writing your own property functions. For example, we could write TENSE, a function to extract the tense from the parse field and then do:

from domain import *

greek_forms = Rel()
greek_forms.load_cols("forms.txt", ("form", "pos", "parse", "lemma"))
greek_forms.query(PartCount(TENSE))

resulting in output like:

=========================================
tense
=========================================
A                                   4106
F                                    749
I                                    525
-                                   8779
P                                   3898
Y                                     36
X                                    779
-----------------------------------------
partitions: 7
=========================================

PartCount also takes an optional given argument to restrict the items considered based on the given characteristic function. We can define domain-specific characteristic functions such as INFINITIVE and do the following:

PartCount(TENSE, given=INFINITIVE),

which will give:

=========================================
tense given infinitive
=========================================
A                                    448
P                                    394
X                                     32
F                                      3
-----------------------------------------
partitions: 4
=========================================

Property functions can be combined with LIST so that

PartCount(LIST(TENSE, VOICE), given=INFINITIVE),

will partition the infinitives based on both TENSE and VOICE:

=========================================
tense, voice given infinitive
=========================================
P P                                   72
A M                                   50
X P                                    9
A A                                  310
P A                                  258
F A                                    1
X M                                    1
F M                                    2
A P                                   88
X A                                   22
P M                                   64
-----------------------------------------
partitions: 11
=========================================

Another query class is CrossTab which takes two characteristic functions and generates a cross-table. It can also optionally be restricted to a given characteristic function:

CrossTab(CASE("N"), ENDS_IN("ος"), given=NOMINAL),

Note that the characteristic function NOMINAL and higher-order characteristic functions CASE and ENDS_IN are domain-specific (it's easy to write your own as you can see below). This results in:

=========================================
case N vs -ος given nominal
=========================================
                  -ος      not
-----------------------------------------
case N     |      595     3508 |     4103
not        |      315     6957 |     7272
-----------------------------------------
           |      910    10465 |    11375
=========================================

Yet another provided query class is Assert which will identify any violations of a particular characteristic function. For example, if you want to assert that present active infinitives (domain-specific characteristic function TVM_IS("PAN")) end in ν (domain-specific characteristic function ENDS_IN("ν")) and show the lemmas (property function LEMMA) of the violators, you use:

Assert(ENDS_IN("ν"), given=TVM_IS("PAN"), display=LEMMA),

It is possible to write your own query classes. In morphology work, for example, I use a query class EndingTree to show the possible endings a given type of word (identified by characteristic function) can have.

EndingTree(given=INFINITIVE),

As mentioned at the start, you can write your own property functions:

def TENSE(t):
    "tense"
    return t["parse"][1]

which can be combined with LIST as we saw above in things like LIST(TENSE, VOICE).

Notice that property functions take an dictionary t and return some string value from that dictionary.

You can also write your own characteristic functions:

def NOMINAL(t):
    "nominal"
    return t["pos"][0] in ["N", "A", "R"] or (t["pos"] == "V-" and t["parse"][3] == "P")

and higher-order characteristic functions (functions which return characteristic functions):

def ENDS_IN(ending):
    def _(t):
        return strip_accents(t["form"]).endswith(ending)
    _.__doc__ = "-{0}".format(ending)
    return _

Characteristic functions can be combined with AND, OR, NOT, ANY and ALL. There are also built-in characteristic functions ALWAYS and NEVER.

Notice that characteristic functions take a dictionary t and return a boolean indicating whether the dictionary has that characteristic.

Note that the doc-strings are very important as they are used as part of the output of query results.

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