dativatools 2.9.16

A selection of tools for easier processing of data using Pandas and AWS

# Dativa Tools

Provides useful libraries for processing large data sets. Developed by the team at [www.dativa.com](https://www.dativa.com) as we find them useful in our projects.

Any questions, please email hello AT dativa.com

## Installation

```
pip install dativatools
```

## Description

The library includes two modules:
* dativatools - which contains the legacy classes
* dativa.tools - which contains the more recent classes.

Over time it is expected that we will migrate all classes over to the dativa.tools module

### dativa.tools.aws.AthenaClient
An easy to use client for AWS Athena that will create tables from S3 buckets (using AWS Glue) and run queries against these tables. It support full customisation of SerDe and column names on table creation.

Examples:

#### Creating tables

The library creates a temporary Glue crawler which is deleted after use, and will also create the database if it does not exist.

```
ac = AthenaClient(aws_region, db_name)
ac.create_table(table_name='my_first_table',
crawler_target={'S3Targets': [
{'Path': 's3://my-bucket/table-data'}]}
)

# Create a table with a custom SerDe and column names, typical for CSV files
ac.create_table(table_name='comcast_visio_match',
crawler_target={'S3Targets': [
{'Path': 's3://my-bucket/table-data-2', 'Exclusions': ['**._manifest']}]},
serde='org.apache.hadoop.hive.serde2.OpenCSVSerde',
columns=[{'Name': 'id', 'Type': 'string'}, {
'Name': 'device_id', 'Type': 'string'}, {'Name': 'subscriber_id', 'Type': 'string'}]
)
```

#### Running queries

```
ac = AthenaClient(aws_region, db_name)
ac.add_query(sql=query,
name="From field {0}".format(test_columns[i]),
output_location=s3_bucket + 'test-processed')

i = i + number_fields + 1

ac.wait_for_completion()
```

#### Fetch results of query

```
ac = AthenaClient(aws_region, db_name)
ac.add_query(sql=query,
name="From field {0}".format(test_columns[i]),
output_location=s3_bucket + 'test-processed')

ac.wait_for_completion()
ac.get_query_result(query)
```

### dativa.tools.aws.S3Client
An easy to use client for AWS S3 that copies data to S3.
Examples:

#### Batch deleting of files on S3

```
# Delete all files in a folder
s3 = S3Client()
s3.delete_files(bucket="bucket_name", prefix="/delete-this-folder/")

# Delete only .csv.metadata files in a folder
s3 = S3Client()
s3.delete_files(bucket="bucket_name", prefix="/delete-this-folder/", suffix=".csv.metadata")

```

#### Copy files from folder in local filesystem to s3 bucket

```
s3 = S3Client()
s3.put_folder(source="/home/user/my_folder", bucket="bucket_name", destination="backup/files")

# Copy all csv files from folder to s3
s3.put_folder(source="/home/user/my_folder", bucket="bucket_name", destination="backup/files", 'file_format="*.csv")
```

### dativa.tools.SQLClient

A SQL client that wraps any PEP249 compliant connection object and provides detailed logging and simple query execution. In provides the following methods:

#### execute_query
Runs a query and ignores any output

Parameters:

- query - the query to run, either a SQL file or a SQL query
- parameters - a dict of parameters to substitute in the query
- replace - a dict or items to be replaced in the SQL text
- first_to_run - the index of the first query in a mult-command query to be executed

#### execute_query_to_df

Runs a query and returns the output of the final statement in a DataFrame.

Parameters:

- query - the query to run, either a SQL file or a SQL query
- parameters - a dict of parameters to substitute in the query
- replace - a dict or items to be replaced in the SQL text


#### def execute_query_to_csv

Runs a query and writes the output of the final statement to a CSV file.

Parameters:

- query - the query to run, either a SQL file or a SQL query
- csvfile - the file name to save the query results to
- parameters - a dict of parameters to substitute in the query
- replace - a dict or items to be replaced in the SQL text

#### Example code

```
# set up the SQL client from environment variables
sql = SqlClient(psycopg2.connect(
database=os.environ["DB_NAME"],
user=os.environ["USER"],
password=os.environ["PASSWORD"],
host=os.environ["HOST"],
port=os.environ["PORT"],
client_encoding="UTF-8",
connect_timeout=10))

# create the full schedule table
df = sql.execute_query_to_df(query="sql/my_query.sql",
parameters={"start_date": "2018-01-01",
"end_date": "2018-02-01"})
```

### dativa.tools.log_to_stdout

A convenience function to redirect a specific logger and its children to stdout

```
log_to_stdout("dativa.tools", logging.DEBUG)
```

### dativa.tools.pandas.CSVHandler

A wrapper for pandas CSV handling to read and write DataFrames with consistent CSV parameters by sniffing the parameters automatically. Includes reading a CSV into a DataFrame, and writing it out to a string. Files can be read/written from/to local file system or AWS S3.

For S3 access suitable credentials should be available in '~/.aws/credentials' or the AWS_ACCESS_KEY_ID/AWS_SECRET_ACCESS_KEY environment variables.

#### CSVHandler

- base_path - the base path for any CSV file read, defaults to ""
- detect_parameters - whether the encoding of the CSV file should be automatically detected, defaults to False
- csv_encoding - the encoding of the CSV files, defaults to UTF-8
- csv_delimiter - the delimeter used in the CSV, defaults to ','
- csv_header - the index of the header row, or -1 if there is no header
- csv_skiprows - the number of rows at the beginning of file to skip
- csv_quotechar - the quoting character to use, defaults to "

#### load_df

Opens a CSV file using the specified configuration for the class and raises an exception if the encoding is unparseable. Detects if base_path is an S3 location and loads data from there if required.

Parameters:

- file - File path. Should begin with 's3://' to load from S3 location.
- force_dtype - Force data type for data or columns, defaults to None

Returns:

- dataframe

#### save_df

Writes a formatted string from a dataframe using the specified configuration for the class the file. Detects if base_path is an S3 location and saves data there if required.

Parameters:

- df - Dataframe to save
- file - File path. Should begin with 's3://' to save to an S3 location.

#### df_to_string

Returns a formatted string from a dataframe using the specified configuration for the class.

Parameters:

- df - Dataframe to convert to string

Returns:

- string

#### Example code
```
from dativa.tools.pandas import CSVHandler

# Create the CSV handler
csv = CSVHandler(base_path='s3://my-bucket-name/')

# Load a file
df = csv.load_df('my-file-name.csv')

# Create a string
str = csv.df_to_string(df)

# Save a file
csv.save_df(df, 'another-path/another-file-name.csv')
```

### Support functions for Pandas

* dativa.tools.pandas.is_numeric - a function to check whether a series or string is numeric
* dativa.tools.pandas.string_to_datetime - a function to convert a string, or series of strings to a datetime, with a strptime date format that supports nanoseconds
* dativa.tools.pandas.datetime_to_string - a function to convert a datetime, or a series of datetimes to a string, with a strptime date format that supports nanoseconds
* dativa.tools.pandas.format_string_is_valid - a function to confirm whether a strptime format string returns a date
* dativa.tools.pandas.get_column_name - a function to return the name of a column from a passed column name or index.
* dativa.tools.pandas.get_unique_column_name - a function to return a unique column name when adding new columns to a DataFrame

### Legacy classes

#### dativatools.CommonUtility
Supports various common activities including getting detailed descriptions about exceptions, logging activity into a CSV file or database table
and sending email reports of failures.

#### dativatools.DataValidation
Class containing methods to validate file sizes, dates, counts, names and extensions at a specified location.

#### dativatools.DatabaseManagement
Generic database management operations including data insertion, table deletion, backup, rename, drop and create as well as query execution.

#### dativatools.RsyncLib
Class to perform file transfer using Rsync.

#### dativatools.SFTPLib
Class to perform file transfer using SFTP.

#### dativatools.ArchiveManager
Class to manage archiving and unarchiving of files to and from specific locations.

#### dativatools.TextToCsvConverter
Class containing methods required to convert a text file to CSV and change certain parameters like headers, separators etc.

#### dativatools.S3Lib
Supports connecting to and getting and putting data to and from AWS S3 buckets.