pbu 0.4.0

Basic Utility module for the Python programming language

Python Basic Utilities pbu

Table of Contents

1. Installation
2. Usage
3. Classes
   1. JSON - a JavaScript-like dictionary access helper
   2. Logger - a wrapper around the Python logging framework
   3. TimeSeries - powerful helper class to organise time series
   4. AbstractMongoStore - helper and wrapper class for MongoDB access
   5. AbstractMysqlStore - helper and wrapper class for MySQL access

Installation

Install via pip:

pip install pbu

Usage

If you have a requirement.txt file, you can add pbu (replace 0.4.0 with latest available version or omit entirely to get the latest):

pbu==0.4.0

Then, simply import the class / module you need:

from pbu import JSON

# and start using it
obj = JSON({"my": {"obj": "content"}})
print(obj.my.obj)

Classes

JSON

This is an adaptation of the native dict class, providing Javascript-like dictionary access using the "dot-notation" (e.g. person.relations[0].address.street) rather than the Python-native bracket notation (e.g. person["relations"][0]["address"]["street"]). It overrides the basic __getattr__ and __setattr__ methods as a shortcut to manage the dictionary content.

Example

from pbu import JSON
my_obj = JSON({"initial": "content"})
print(my_obj.initial)
# prints out "content"

my_obj.initial = {"a": 5, "b": 3}
print(my_obj.initial.a + my_obj.initial.b)
# prints out 8
my_obj.initial.b = 13
print(my_obj.initial.a + my_obj.initial.b)
# prints out 18

my_obj.extension = 10
print(my_obj.extension)
# prints out 10

Logger

This is a basic logger allowing to write log files, for logger.info it writes a debug.log and for logger.error or logger.exception it writes an error.log file.

Example

from pbu import Logger

logger = Logger(name="logger-name")
logger.debug("Some debug message goes here")
logger.error("Error executing something")

logger = Logger(name="logger-name", log_folder="./logs")
logger.debug("This will create the debug.log and error.log in the ./logs folder")

TimeSeries

The time series class is a helper utility, that allows to compile complex time-series, offering functionality to add time series, remove time series and most importantly align time series with timestamps to a previously defined resolution by interpolating missing values and re-aligning measurements within the tolerance of the provided time series.

It supports 2 different structures:

List of Dictionary Items

from datetime import datetime, timedelta

list_of_dict = [
    { "date_time": datetime.now(), "measurement_1": 12, "measurement_2": 15 },
    { "date_time": datetime.now() + timedelta(hours=1), "measurement_1": 10, "measurement_2": 16 },
    { "date_time": datetime.now() + timedelta(hours=2), "measurement_1": 9, "measurement_2": 12 },
]

Dictionary of Lists

from datetime import datetime, timedelta

dict_of_list = {
    "date_time": [datetime.now(), datetime.now() + timedelta(hours=1), datetime + timedelta(hours=2)],
    "measurement_1": [12, 10, 16],
    "measurement_2": [15, 16, 12],
}

Example

from pbu import TimeSeries
from datetime import datetime, timedelta

# initial time series base data (you can add measurements as well or provide as list of dictionaries
dict_of_list = {
    "date_time": TimeSeries.create_date_range(datetime.now(), datetime.now() + timedelta(days=1), timedelta(hours=3)),
}

# init time series
ts = TimeSeries(input_data=dict_of_list, date_time_key="date_time")
# add values (ensure same length as date_time series)
ts.add_values("measurement_1", [12, 10, 16, 10, 5, 8, 12, 9])  

# you can translate into a list of dictionary items (keys are maintained)
list_of_dict = ts.translate_to_list_of_dicts()

# extract data series from the time series
measurement_1 = ts.get_values("measurement_1")

# create new series that provides same value for all timestamps
ts.fill_values("constant_series", 5)

# remove a series from the total data structure
ts.remove_series("constant_series")

# re-sample data to 5 minute resolution, interpolating values, also pre-pending another day in front of the time series 
ts.align_to_resolution(resolution=timedelta(minutes=5), start_date=datetime.now() - timedelta(days=1))
# this will result in "interpolated" values for the first day, using the first value (12) to fill missing values
print(len(ts.translate_to_list_of_dicts()))  # 12 an hour, 2 days, 48 * 12 = ~576 items

# the same can also be achieved by:
ts.set_resolution(timedelta(minutes=5))
# no need to provide resolution now
ts.align_to_resolution(start_date=datetime.now() - timedelta(days=1))

AbstractMongoStore

Database store with helper functions for accessing MongoDB. Each store instance represents a single collection. This comes with an AbstractMongoDocument class, which can be used to model the document types you store within a MongoDB collection.

Example

from pbu import AbstractMongoStore, AbstractMongoDocument

# this is the object type stored in the mongo store
class MyObjectType(AbstractMongoDocument):
    def __init__(self, val1, val2):
        # optional: provide id and data model version 
        super().__init__()
        self.attribute = val1
        self.attribute2 = val2,
    def to_json(self):
        # init with version and id
        result = super().to_json()
        # add attributes to dictionary and return
        result["attribute"] = self.attribute
        result["attribute2"] = self.attribute2
        return result

    @staticmethod
    def from_json(json):
        result = MyObjectType(json["attribute1"], json["attribute2"])
        # get _id and version attributes
        result.extract_system_fields(json)
        return result


class MyObjectStore(AbstractMongoStore):
    def __init__(self, mongo_url, db_name, collection_name, data_model_version):
        # provide object type class as de-serialisation class (providing from_json and to_json)
        super.__init__(mongo_url, db_name, collection_name, MyObjectType, data_model_version)


# create instance of store
store = MyObjectStore("mongodb://localhost:27017", "mydb", "colName", 5)

# create document using a dictionary
store.create({
    "version": 5,
    "attribute1": "a",
    "attribute2": 16,
})

# or use the type
doc = MyObjectType("a", 16)
doc.version = 5
doc_id = store.create(doc)

# update single document using helper functions
store.update(AbstractMongoStore.id_query(doc_id), 
             AbstractMongoStore.set_update(["attribute1", "attribute2"], ["b", 12]))


# returns a list of MyObjectType objects matching the version
list_of_results = store.query({ "version": 5 })