Pandas vs. SQL – Tools that Data Scientists use most often.pdf

Pandas vs. SQL – Tools that Data Scientists
use most often
There is an ongoing discussion related to the best tool that is highly been used by
Data Scientists to perform their tasks at the workplace. In their job role, it is very
important to know the usage of deploying various data tools as they are very helpful
for the process of data analysis. Exploring several data sets and understanding their
structure, content, and relationships is a day-to-day task for every Data Scientist.
There are several tools that exist for performing those tasks.
In this article, let’s understand the most important tools that offer several
functionalities to perform several tasks that are related to big data – Pandas and SQL,
as they are highly considered for the tasks that are related to data mining and
manipulations. They provide various approaches which are very helpful to perform
data analysis. These tools play a very essential role in the job role of data
scientists, data analysts, and professionals who work in the field of business
intelligence.
Now, let’s dive deeper to gain in-depth insights into each tool, know their differences
and various key commands to generate random data and analyze it briefly.
Pandas Vs SQL
Pandas and SQL may look quite same, but their nature is varied in many ways. Pandas
mainly store data in the form of table-like objects and also provide a vast range of
methods to transform those. This aspect makes it a preferred tool for the process of
data analysis.
Whereas, SQL is a declarative language, which is designed to gather, transform and
prepare the datasets. If data resides in a relational database, letting a database engine
perform the steps is a good way. The engines are usually optimized to perform those
tasks, they also let the database prepare a clean and convenient dataset, which
facilitates the analysis process.
Let’s have a look at the key differences between Pandas and SQL.
Pandas SQL
Setup is easy Setup needs tuning and optimization of the query
Complexity is less since it is just a package that
requires being imported
Configuration and other database configurations give
more complexity and time of execution
Reliability and scalability are less Reliability and scalability are much better
Security is compromised
Security is higher due to Atomicity, Consistency,
Isolation, and Durability (ACID) properties

Pandas SQL
Math, statistics, and procedural approaches like
User Defined Functions (UDF) are handled
efficiently
Math, statistics, and procedural approaches like User
Defined Functions (UDF) are not performed well
enough
Cannot be easily integrated with other languages
and applications
Can be easily integrated to offer support with all
languages
People with good technical knowledge can do data
manipulation operations
Very easy to read, understand since SQL is a
structured language
Now, let’s understand the about the Pandas and few important commands that are
highly helpful.
Pandas
Python supports an in-built library Pandas, which is an open-source data analysis tool.
Pandas is very useful to perform the tasks that are related to data analysis where the
process of manipulation is done very quickly with more efficiency. Pandas library
effectively manages data available in uni-dimensional arrays, which are as called
‘Series’, and multi-dimensional arrays called ‘Data Frames.’
Python offers a huge variety of in-built functions and utilities to perform data
transforming and manipulations. Statistical modeling, filtering, file operations,
sorting, and import or export with the NumPy module are a few vital features of the
Pandas library. Huge amounts of data are managed and mined in a better and most
user-friendly way.
 To build calculated fields from existing features
In Pandas, one can simply divide features much easier when compared to
SQL.
df["latest_column"] = df["first_column"]/df["second_column"]
The aforementioned code clearly states that how to divide the two
separate columns and assigning those values to the latest column. In this
case, one can do the feature creation task on the entire dataset. This is
helpful for both feature exploration and feature engineering in the
process of data science.
Pandas are very helpful when the data is already in a file format (.csv,
.txt, .tsv, etc). It also gives an option to perform tasks on data sets
without impacting database resources.
 Converting file into data frame - pandas.read_csv()
Initially, it is required to pull the data into a data frame. Once it is set to
a variable name (‘df’ below), one can use the other functions to analyze

and manipulate the data. Here, let’s take the ‘index_col’ parameter while
loading the data into a data frame. This parameter is setting the first
column (index = 0) as the row labels for the data frame.
 # Command to import the pandas library to the
notebook
 import pandas as pd

 # Read data from Titan dataset.
 df = pd.read_csv('...titan.csv', index_col=0)
 # Location of file, will be url or local folder structure

 The ‘head’ command - pandas.head()
The head function is very useful in previewing what the data frame looks
like after it has been loaded. The default can be shown as many rows as
one wants to, but one will have the option to adjust it by just typing
.head (10).
df.head()
 The ‘info’ command - pandas.info()
The info function will provide a breakdown of the data frame columns
and the non-null entries that each has. It also tells gives the kind of data
type is for each column and the number of total entries that are available
in the data frame.
df.info()
 The ‘describe’ command - pandas.describe()
The describe function is very helpful to get the distribution of the data,
particularly numerical fields like ints and floats. It returns a data frame
with the mean, min, max, standard deviation, etc. for each column.
df.describe()

Moving on, let’s see about SQL and what are its important commands,
which are highly used.
SQL
Structured Query Language (SQL) is a domain-specific language, which is very
helpful in programming and designed for managing data held in a Relational Database
Management System (RDBMS). The usage of SQL is quite impressive in various
places due to its functionalities. For instance, SQL can be used by data engineers,
Tableau developers, or even product managers. Many data scientists use SQL
frequently. It is very crucial to know that there are many various versions of SQL,
which consists of similar function, but slightly vary.
 INSERT command
 INSERT INTO account (‘A/c number’,‘first Name’,‘last Name’)
 VALUES (‘123456789’,‘Rachael’,’ Scott’);
 UPDATE command
 UPDATE account
 SET contact number = 9988776655
 WHERE A/c number = ‘123456789’
 DELETE command
 DELETE FROM account
 WHERE e-mail address = ‘rs1991@hotmail.com’;

 JOIN command
One of the best aspects of SQL is the JOIN command. To explain it in
simple words, the JOIN command makes the database ‘relational’. JOIN
gives the user to link data from two or more tables in a single query by
using of single ‘SELECT’ command.
For instance, one can easily get related data in multiple tables with the
help of a single SQL statement, which gives A/c number, first name, and
respective branch.
 SELECT A/c number, first name, Branch

 FROM account
 LEFT JOIN last name ON A/c type;
Pandas or SQL: Which tool should a Data Scientist use?
Pandas usually lag for massive volumes of data but it has several functions that are
helpful for the Data Scientists to manipulate data in an impressive way. Whereas SQL
is highly efficient in querying data but it consists of fewer functions.
Pandas are highly recommended if a Data Scientist wants to manipulate the data or for
plotting, as it is easier to analyze data with special plotting features that offer a faster
plot to acquire in-detail insights into the data. Whereas SQL has to use Tableau
for data visualization.
To summarize
Pandas and SQL are very effective tools. At places where simple data manipulations,
like data retrieval, handling, join, filtering is done. SQL is helpful as it is easy to use.
But, for massive data mining and manipulations, the query optimizations, Pandas is
the best option. It is very important one should have a clear understanding so that they
pick the right tool to perform certain data science tasks effectively.

Pandas vs. SQL – Tools that Data Scientists use most often.pdf

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Pandas vs. SQL – Tools that Data Scientists use most often.pdf