In this article, we will learn What is a CSV in Python?, How to read a CSV file in Python? How to write a CSV file in Python?, What are modules in python? and What are packages in python?.
What is a CSV in Python? with example
The simple CSV (Comma Separated Values) file format is used to store tabular data in databases and spreadsheets. Tabular data (numbers and text) is stored as plain text in a CSV file. The file’s lines each contain a data record. There are one or more fields in each record, and commas are used to divide them. The fact that fields are separated by commas is how this file format got its name.
There is a built-in module in Python called CSV that allows you to work with CSV file
CSV module examples
# import CSV from the CSV module # My data rows are objects in a dictionary. on edict = ['branch': 'COE', 'cgpa': '9.0', 'name': 'Nikhil', 'year': '2', 'branch': 'COE', 'cgpa': '9.1', 'name': 'Sanchit', 'year': '2', 'branch': 'IT', 'cgp Number of field names: ["name," "branch," "year," "cgpa"] # Filename: The CSV file's name is "university records.csv." # Using open(filename, 'w') as CSV file to write to a CSV file: object writer = CSV.DictWriter(CSV file, field names = fields) for constructing a CSV dict writer making headers (field names) writer.write header() Writer. write rows is # writing data rows (mydict) read a CSV in Python
How to read a CSV file in Python is described below
Step 1: Use the reader function to create a reader object in order to read data from CSV files.
The reader function is designed to accept each file row and create a list of all the columns for that row. The next step is to select the column for which you want the variable data.
It sounds much more complicated than it really is. Let’s examine this Python code to read a CSV file to see how simple it is to work with CSV files.
#import necessary modules
import CSV
with open('X:\data.CSV,'rt')as f:
data = CSV.reader(f)
for row in data:
print(row)
Step 2) The outcome of running the aforementioned application will be
['Programming language; Designed by; Appeared; Extension'] ['Python; Guido van Rossum; 1991; .py'] ['Java; James Gosling; 1995; .java'] ['C++; Bjarne Stroustrup;1983;.cpp']
How to write CSV File in Python?
Here is a Python tutorial on creating a CSV file:
Use the writer() function whenever you have a set of data that you want to save in a CSV file. You must use the writer () function to loop through the data in rows (or lines).
Consider the case below. We enter data into the file “writeData.csv” with an apostrophe as the delimiter.
#import necessary modules
import csv
with open('X:\writeData.csv', mode='w') as file:
writer = csv.writer(file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL)
#way to write to csv file
writer.writerow(['Programming language', 'Designed by', 'Appeared', 'Extension'])
writer.writerow(['Python', 'Guido van Rossum', '1991', '.py'])
writer.writerow(['Java', 'James Gosling', '1995', '.java'])
writer.writerow(['C++', 'Bjarne Stroustrup', '1985', '.cpp'])
Write to CSV file
The simple CSV (Comma Separated Values) file format is used to store tabular data in databases and spreadsheets. Tabular data (numbers and text) is stored in CSV files as plain text. The file’s lines each contain a data record. Each record contains one or more fields that are separated by commas. The fact that fields are separated by commas is how this file format got its name.
Python comes with a built-in module called CSV that allows you to work with CSV files. This module offers a number of classes for writing to CSV, including:
- CSV.writer class use
- CSV.DictWriter class use
Using CSV.writer class
The CSV file is filled with data using the CSV. writer class. The writer object that these class returns are in charge of transforming the user’s data into a delimited string. Opening a CSV file object with newline=” prevents newline characters from being misinterpreted inside quoted fields.
Parameters:
A file object containing the write() method is a CSV file.
Name of the dialect to be used, if provided.
Formatting parameters that will replace those supplied in the dialect are called fmtparams (optional).
There are two ways to write to CSV using the CSV. writer class. Writerow() and Writerows are them ().
The writers() method only writes one row at a time. This approach allows for the writing of field rows.
Syntax:
Write numerous rows at once using the writers() function. A row list can be written with this.
Syntax:
CSV file creation using Python write rows (rows)
Example:
# Python program to demonstrate # writing to CSV import CSV # field names fields = ['Name', 'Branch', 'Year', 'CGPA'] # data rows of CSV file rows = [ ['Nikhil', 'COE', '2', '9.0'], ['Sanchit', 'COE', '2', '9.1'], ['Aditya', 'IT', '2', '9.3'], ['Sagar', 'SE', '1', '9.5'], ['Prateek', 'MCE', '3', '7.8'], ['Sahil', 'EP', '2', '9.1']] # name of CSV file filename = "university_records.csv" # writing to CSV file with open(filename, 'w') as CSV file: # creating a CSV writer object CSV writer = CSV.writer(csvfile) # writing the fields CSV writer.writers(fields) # writing the data rows csvwriter.writers(rows)
How to read CSV files In python
The most popular import and export format for databases and spreadsheets is known as CSV (Comma Separated Values). The CSV format was in use for a long time before RFC 4180’s attempts to standardize its description. Because there isn’t a clear standard, there are frequently little discrepancies between the data that various apps produce and consume. The processing of CSV files from several sources might be troublesome due to these discrepancies. However, even though the delimiters and quotation characters differ, the general structure is similar enough that it is possible to create a single module that can effectively manipulate such data while keeping the programmer from knowing the specifics of reading and writing the data.
The CSV module implements classes for reading and writing tabular data in CSV format. Without being aware of the specifics of the CSV format that Excel uses, it enables programmers to say things like, “put this data in the format favored by Excel,” or “read data from this Excel-generated file,” etc. Additionally, programmers can define the CSV formats that other programs can recognize or create their own specialized CSV formats.
Python export to CSV
You can export your Pandas DataFrame to a CSV file using the Python template shown below:
File Name.csv, index = False, df.to csv(r'Path where you want to save the exported CSV file),
Additionally, just remove ", index = False" from the code if you want to include the index:File Name.csv, df.to csv(r'Path where you wish to save the exported CSV file')
what are python libraries?
A library is typically a collection of books, a room, or a location where many books are kept for future use. A library is a collection of precompiled routines that can be utilized later in a program for a few specific, well-defined operations. A library could also include configuration information, message templates, classes, values, and other things aside from pre-compiled scripts.
The term “Python library” refers to a group of connected modules. It has collections of code that can be utilized repeatedly in many programs. For the programmer, it simplifies and makes Python programming more practical. Since we don’t have to write the same code for many apps repeatedly. In the domains of machine learning, data science, data visualization, etc., python libraries are quite important.
What are modules in python?
Simple files with the “.py” suffix that contain Python code are known as modules in Python and can be imported into other Python programs.
If you want to use a collection of functions in your application, you can think of a module as being similar to a code library or a file.
We can group related functions, classes, or any other type of code block in the same file using modules. Therefore, it is thought to be best practice to break up large Python code blocks into modules of up to 300–400 lines of code when building larger codes for production-level projects in data science.
The following elements are included in the module: class definitions and implementation, factors, and functionalities that can be accessed from within another program. Let’s use an illustration to help you better understand the idea:
Say our goal is to develop a calculator application. A few operations, such as addition, subtraction, multiplication, and division, are what we wish to include in our program.
Now, what we will do is just build one module for all of these operations or different modules for each operation by breaking the entire code into separate portions. Then, in the logic of our main program, we can call these modules.
The main goal in this situation is to keep the amount of code to a minimum. If we construct modules, that doesn’t imply we can just use them for this application; we may also call these modules from other programs.
What are packages in python?
On the other hand, a module is a Python program that you import into other programs or into interactive mode. The name “module” is actually a catch-all for reusable code.
Typically, a Python package is made up of numerous modules. A package is a folder that physically contains modules as well as maybe other folders that in turn may include still more folders and modules. In terms of concept, it’s a namespace. This merely means that a package’s modules are linked together by a name that may be used to refer to them.
In reference to our earlier definition of a module as reusable, importable code, we should point out that while every package is a module, not every module is a package. One file called __init .py is typically found in a package folder, and it basically informs Python, “Hey, this directory is a package!” The init file may be blank or it may have code that will run when the package is initialized.
Probably as well, you’ve heard the word “library.” Although a library’s definition in Python is less explicit than that of a package or a module, it is generally accepted that if a package has been made public, it may also be referred to as a library.
which system variable is used to read the text and csv files?
To read text and CSV files, Automation Anywhere makes use of a system variable named Table Column.
To read text and CSV files, automation employs a system variable called table column. Fewer resources are required to read text and CSV files. These types of files can be read without the user having to start a new system application. Form tables can be utilized everywhere for such files as an automatic function.
Double-clicking or dragging the CSV/TXT package to that location will select the Open action.
Select one of the options below to specify the location of the CSV or text file to open:
Click the Contains header box if the file has a header row and you want to receive the values from that row.
Using the command line, navigate to the Desktop, then type cat myFile.txt. This will output the contents of the file on your command line. The idea here is the same as when you double-click a text file in the GUI to see what’s within.
