How to Read a CSV File in Python

How to Read a CSV File in Python How to Read CSV File in Python? 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It essentially stores a tabular data which comprises of numbers and text into plain text. Most of the online services give users the liberty to export data from the website into CSV file format. CSV Files generally open into Excel and nearly all the databases have different specific tools to allow the import of the same.Every line of the file is called a record. And each record consists of fields that are separated by commaswhich are also known as delimiter which is the default delimiter, others include pipe(|), semicolon(;). Given below is a structure of a Normal CSV File separated by a comma, I am making use of a titanic CSV file.StructurePassenger,Id,Survived,Pclass,Name,Sex.Age 1,0,3 Braund, Mr. Owen Harris ,male, 22 2,1,1 Cumings, Mrs. John Bradley (Florence Briggs Thayer), female,38 3,1,3 Heikkinen, Miss. Laina ,female, 26 4,1,1 Futrelle, Mrs. Jacques Heath (Lily May Peel),female,35Moving on lets talk about the reason behind usage of CSV File format. Why is CSV File Format Used?CSV is a plain-text file which makes it easier for data interchange and also easier to import onto spreadsheet or database storage. For example: You might want to export the data of a certain statistical analysis to CSV file and then import it to the spreadsheet for further analysis. Overall it makes users working experience very easy programmatically. Any language supporting a text file or string manipulation like Python can work with CSV files directly. Moving ahead, lets see how Python natively uses CSV.Python CSV modulePython uses a CSV package which is a part of the standard library, so you need not install it. import csv Now let me show you the different CSV functions.CSV Module FunctionsUnder the CSV module, you can find the following functions:FunctionsDescriptioncsv.field_size_limitIt returns the maximum field sizecsv.get_dialectFetches the dialect associated with namecsv.list_dialectsDisplays all the registered dialectscsv.readerRead data from csv filecsv.register_dialectDialect associated with a namecsv.writerWrites data to a csv filecsv.unregister_dialectIt deletes the dialect associated with the name dialect registrycsv.QUOTE_ALLQuotes everything irrespective of the typecsv.QUOTE_MINIMALQuotes special character fieldcsv.QUOTE_NONNUMERICQuotes fields that are not numeralcsv.QUOTE_NONE Doesnt quote anything in outputLets move ahead and see from the coding perspective of the different operations on the CSV file in Python.Operations On CSV file in PythonYou can perform several manipulations once a CSV file is loaded. I am going to show the read and write operations on a CSV file in Python.Read CSV file in Python: import csv with open('Titanic.csv','r') as csv_file: #Opens the file in read mode csv_reader = csv.reader(csv_file) # Making use of reader method for reading the file for line in csv_reader: #Iterate through the loop to read line by line print(line) Output: Here, as you can see from the output, I have made use of Titanic CSV File. And all the fields are separated by a comma, File is read into Python.Moving ahead, lets see how you can write to a CSV file.Write to CSV file in Python: import csv with open('Titanic.csv', 'r') as csv_file: csv_reader = csv.reader(csv_file) with open('new_Titanic.csv', 'w') as new_file: # Open a new file named 'new_titanic.csv' under write mode csv_writer = csv.writer(new_file, delimiter=';') #making use of write method for line in csv_reader: # for each file in csv_reader csv_writer.writerow(line) #writing out to a new file from each line of the original file Output: Now this way of working with CSV file using a reader and writer method is one of the most common approaches. Lets move on and see how you can do the same thing using a python dictionary. Read CSV file as Dictionary: import csv with open('Titanic.csv','r') as csv_file: #Open the file in read mode csv_reader = csv.DictReader(csv_file) #use dictreader method to reade the file in dictionary for line in csv_reader: #Iterate through the loop to read line by line print(line) Output: As you can see from the output, field has been replaced and they now act as a key of dictionary.Lets see how we can write to a CSV file as dictionary.Write to CSV file as Dictionary import csv mydict = [{'Passenger':'1', 'Id':'0', 'Survived':'3'}, #key-value pairs as dictionary obj {'Passenger':'2', 'Id':'1', 'Survived':'1'}, {'Passenger':'3', 'Id':'1', 'Survived':'3'}] fields = ['Passenger', 'Id', 'Survived'] #field names filename = 'new_Titanic.csv' #name of csv file with open('new_Titanic.csv', 'w')as new_csv_file: #open a new file 'new_titanic,csv' under write mode writer = csv.DictWriter(new_csv_file, fieldnames=fields) writer.writeheader() #writing the headers(field names) writer.writerows(mydict) #writing data rows Output: Lets see how to read a CSV file in python as pandas.Read CSV file as Pandas: import pandas #install pandas package result = pandas.read_csv('Titanic.csv') #read the csv file print(result) # print result Output: This brings us to the end of our article How to read CSV File in Python. I hope you are clear with all the concepts related to CSV, how to read and write it, how to read and write CSV as a dictionary and how to read CSV as pandas.Make sure you practice as much as possible and revert your experience.Got a question for us? Please mention it in the comments section of this How to read CSV File in Python article and we will get back to you as soon as possible. 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