pycof 1.1.16

A package for commonly used functions

PYCOF (PYthon COmmon Functions)

1. Installation

You can get pycof from PyPI with:

pip install pycof

The library is supported on Windows, Linux and MacOs.

2. Usage

2.1. Config file for credentials

2.1.1. Save your credentials locally

The function remote_execute_sql and send_email will by default look for the credentials located in /etc/config.json. On Windows, save the config file as C:/Windows/config.json.

The file follows the below structure:

{
	"DB_USER": "",
	"DB_PASSWORD": "",
	"DB_HOST": "",
	"DB_PORT": "3306",
	"DB_DATABASE": "",
	"__COMMENT_1__": "Email specific, send_email"
	"EMAIL_USER": "",
	"EMAIL_PASSWORD": "",
	"EMAIL_SMTP": "smtp.gmail.com",
	"EMAIL_PORT": "587"
	"__COMMENT_2__": "IAM specific, if useIAM=True in remote_execute_sql",
	"CLUSTER_NAME": "",
	"AWS_ACCESS_KEY_ID": "",
	"AWS_SECRET_ACCESS_KEY": "",
	"REGION": "eu-west-1"
}

On Unix based system, run:

sudo nano /etc/config.json

and paste the above json after filling the empty strings (pre-filled values are standard default values).

Reminder: To save the file, with nano press CTRL + O, confirm with y then CTRL + X to exit.

On Windows, use the path C:/Windows/config.json.

2.1.2. Pass your credentials in your code

Though it is highly not recommended, you can pass your credentials locally to the functions with the argument credentials. You can then create a dictionnary using the same keys as described in previous section.

The preferred option is to provide the json file's path to the credentials argument.

2.2. Load PYCOF

To load pycof in your script, you can use:

# Load pycof
import pycof as pc

# Or, load a specific function or all functions from pycof
from pycof import *

2.3. Available functions

The current version of the library provides:

• verbose_display: extended function to print strings, lists, data frames and progression bar if used as a wrapper in for loops.
• remote_execute_sql: aggragated function for SQL queries to SELECT, INSERT, DELETE or COPY.
• send_email: simple function to send email to contacts in a concise way.
• add_zero: simple function to convert int to str by adding a 0 is less than 10.
• OneHotEncoding: performs One Hot Encoding on a dataframe for the provided column names. Will keep the original categorical variables if drop is set to False.
• create_dataset: function to format a Pandas dataframe for keras format for LSTM.
• group: will convert an int to a str with thousand seperator.
• replace_zero: will transform 0 values to - for display purposes.
• week_sunday: will return week number of last sunday date of a given date.
• display_name: displays the current user name. Will display either first, last or full name.
• write: writes a str to a specific file (usually .txt) in one line of code.
• str2bool: converts string to boolean.
• wmape: computes the Weighted Mean Absolute Percentage Error between two vectors.
• mse: computes the Mean Squared Error between two vectors. Returns the RMSE (Root MSE) if root is set to True.

3. FAQ

3.1. How to use remote_execute_sql?

The function executes a given SQL query with credentials automatically pulled from /etc/config.json. To execute an SQL query, follow the below steps:

from pycof as pc

## Set up the SQL query
sql = "SELECT * FROM SCHEMA.TABLE LIMIT 10"

## The function will return a pandas dataframe
df = pc.remote_execute_sql(sql)

You can also cache your data by using the cache argument:

## Cache the results of the query for 1h (60*60 = 3600 seconds)
df = pc.remote_execute_sql(sql, cache=True, cache_time=3600)

The cache argument will allow you to save time the next time you execute the same SQL query within the cache_time period. It will then load the cached data and not execute the whole SQL query. The default value is 1 day.

3.2. Can I query a Reshift cluster with IAM user credentials?

The function remote_execute_sql can take into account IAM user's credentials. You need to ensure that your credentials file /etc/config.json includes the IAM access and secret keys with the Redshift cluster information. The only argument to change when calling the function is to set useIAM=True.

The function will then use the AWS access and secret keys to ask AWS to provide the user name and password to connect to the cluster. This is a much safer approach to connect to a Redshift cluster than using direct cluster's credentials.

You can also play with IAM roles by not specifying the access and secret keys, provided that you host has the required permissions.

Example:

import pycof as pc

## Set the SQL query
sql = "SELECT * FROM SCHEMA.TABLE LIMIT 10"

## Run the query
df = pc.remote_execute_sql(sql, useIAM=True)

3.3. What if I change an argument in the SQL query and run with cache=True?

The function remote_execute_sql looks at your SQL query as a whole when saving/loading the cache data. Even a slight change in the query (column name, filter, etc...) will trigger a new run of the new query before being cached again. You can then safely use caching without worrying about the eventual evolution of your SQL.

3.4. How to use different credential sets?

The credentials argument can take the path or json file name into account to load them.

For instance, you can have multiple credential files such as /etc/config.json, /etc/MyNewHost.json and /home/OtherHost.json. In remote_execute_sql you can play with the credentials argument.

• To use the /etc/config.json credentials you can use the default arguments by not providing anything.
• To use /etc/MyNewHost.json you can either pass MyNewHost.json or the whole path to use them.
• To use /home/OtherHost.json you need to pass the whole path.

Example:

import pycof as pc

## Set the SQL query
sql = "SELECT * FROM SCHEMA.TABLE LIMIT 10"

## Run the query
df = pc.remote_execute_sql(sql, credentials='MyNewHost.json')

3.5. How to use send_email?

The function send_email takes allows to send an email to a given recipient with a specific subject. Similar to remote_execute_sql, the function will automatically pull the credentials from /etc/config.json unless you pass a dictionnary or a path.

Example:

import pycof as pc

## Write the content of the email as HTML
content = """
Hello,
<br><br>
This is a test email using <a href = 'https://pypi.org/project/pycof/'>PYCOF</a>, check it out!
"""

## Send the email
pc.send_email(to='[e-mail]', body=content, subject='Hello world!')

You can choose to copy some other users with the cc argument and choose a different credential set, as explained above.