Data file handling in python binary & csv files

KVS RO AGRA BINARY FILES & CSV(COMMA SEPARATED VALUES) FILES

KVS RO AGRA CREATING BINARY FILES

KVS RO AGRA Content of binary file which is in codes. SEEING CONTENT OF BINARY FILE

KVS RO AGRA READING BINARY FILES TROUGH PROGRAM CONTENT OF BINARY FILE

KVS RO AGRA PICKELING AND UNPICKLING USING PICKLE MODULE

KVS RO AGRA PICKELING AND UNPICKLING USING PICKEL MODULE Use the python module pickle for structured data such as list or directory to a file. PICKLING refers to the process of converting the structure to a byte stream before writing to a file. while reading the contents of the file, a reverse process called UNPICKLING is used to convert the byte stream back to the original structure.

KVS RO AGRA PICKLING AND UNPICKLING USING PICKEL MODULE Firstly we need to import the pickle module, It provides two main methods: 1) dump() method 2) load() method

KVS RO AGRA pickle.dump() Method

KVS RO AGRA pickle.dump() Method pickle.dump() method write the object in binary file. Syntax of dump method is: dump(object ,fileobject)

KVS RO AGRA pickle.dump() Method # A program to write list sequence in a binary file

KVS RO AGRA pickle.load() Method

KVS RO AGRA pickle.load() Method pickle.load() method is used to read the binary file. CONTENT OF BINARY FILE

KVS RO AGRA BINARY FILE R/W OPERATION USING PICKLE MODULE import pickle Wr_file = open(r"C:UserslenovoDesktoppython filesbin1.bin", "wb") myint = 56 mylist = ["Python", "Java", "Oracle"] mystring = "Binary File Operations" mydict = { "ename": "John", "Desing": "Manager" } pickle.dump(myint, Wr_file) pickle.dump(mylist, Wr_file) pickle.dump(mystring, Wr_file) pickle.dump(mydict, Wr_file) Wr_file.close() R_file = open(r"C:UserslenovoDesktopbin1.bin", "rb") i = pickle.load(R_file) s = pickle.load(R_file) l = pickle.load(R_file) d = pickle.load(R_file) print("myint = ", I) print("mystring =", s) print("mylist = ", l) print("mydict = ", d) R_file.close()

KVS RO AGRA READING BINARY FILE THROUGH LOOP Read objects one by one through loop import pickle Wr_file = open(r"C:UserslenovoDesktoppython filesbin1.bin", "wb") myint = 56 mylist = ["Python", "Java", "Oracle"] mystring = "Binary File Operations" mydict = { "ename": "John", "Desing": "Manager" } pickle.dump(myint, Wr_file) pickle.dump(mylist, Wr_file) pickle.dump(mystring, Wr_file) pickle.dump(mydict, Wr_file) Wr_file.close() with open(r"C:UserslenovoDesktopbin1.bin", "rb") as f: while True: try: r=pickle.load(f) print(r) print("Next item") except EOFError: break f.close()

KVS RO AGRA INSERT/APPEND RECORD IN A BINARY FILE Here we are creating dictionary Object to dump it in a binary file import pickle Empno = int(input('Enter Employee number:')) Ename = input('Enter Employee Name:') Sal = int(input('Enter Salary')) #Creating the dictionary dict1 = {'Empno':Empno,'Name':Ename,'Salary':Sal} #Writing the Dictionary f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'ab') pickle.dump(dict1,f) f.close() f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'rb') while True: try: dict1 = pickle.load(f) print('Employee Num:',dict1['Empno']) print('Employee Name:',dict1['Name']) print('Employee Salary:',dict1['Salary']) except EOFError: break f.close()

KVS RO AGRA SEARCH RECORD IN A BINARY FILE import pickle f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'rb') Found = False eno=int(input("Enter Employee no to be searched")) while True: try: dict1 = pickle.load(f) if dict1['Empno'] == eno: print('Employee Num:',dict1['Empno']) print('Employee Name:',dict1['Name']) print('Salary',dict1['Salary']) Found = True except EOFError: break if Found == False: print('No Records found') f.close()

KVS RO AGRA UPDATE RECORD OF A BINARY FILE import pickle f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'rb') rec_File = [] r=int(input("enter Employee no to be updated")) m=int(input("enter new value for Salary")) while True: try: onerec = pickle.load(f) rec_File.append(onerec) except EOFError: break f.close() no_of_recs=len(rec_File) for i in range (no_of_recs): if rec_File[i]['Empno']==r: rec_File[i]['Salary'] = m f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'wb') for i in rec_File: pickle.dump(i,f) f.close()

KVS RO AGRAimport pickle f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'rb') rec_File = [] e_req=int(input("enter Employee no to be deleted")) while True: try: onerec = pickle.load(f) rec_File.append(onerec) except EOFError: break f.close() f = open(r"C:UserslenovoDesktoppython filesEmp.dat",'wb') for i in rec_File: if i['Empno']==e_req: continue pickle.dump(i,f) f.close() DELETE RECORD OF A BINARY FILE

KVS RO AGRA COMMA SEPARATED VALUE(CSV Files)

KVS RO AGRA CSV FILE • CSV is a simple file format used to store tabular data, such as • a spreadsheet or database. • Files in the CSV format can be imported to and exported from programs that store data in tables, such as Microsoft Excel or OpenOffice Calc. • CSV stands for "comma-separated values“. • A comma-separated values file is a delimited text file that uses a comma to separate values. • Each line of the file is a data record. Each record consists of one or more fields, separated by commas. The use of the comma as a field separator is the source of the name for this file format

KVS RO AGRA • One line for each record • Comma separated fields • Space-characters adjacent to commas are ignored • When data has a strict tabular structure • To transfer large database between programs • To import and export data to office applications, Qedoc modules CSV File Characteristics WHEN USE CSV?

KVS RO AGRA • CSV is faster to handle • CSV is smaller in size • CSV is easy to generate • CSV is human readable and easy to edit manually • CSV is simple to implement and parse • CSV is processed by almost all existing applications • No standard way to represent binary data • There is no distinction between text and numeric values • Poor support of special characters and control characters • CSV allows to move most basic data only. Complex configurations cannot be imported and exported this way • Problems with importing CSV into SQL (no distinction between NULL and quotes) CSV Advantages CSV Disadvantages

KVS RO AGRA CSV file handling in Python To perform read and write operation with CSV file, • we must importcsv module. • open() function is used toopen file, and return file object.

KVS RO AGRA WRITING DATA IN CSV FILE  import csv module  Use open() to open CSV file by specifying mode “w” or “a”, it will return file object.  “w” will overwrite previous content  “a” will add content to the end of previous content.  Pass the file object to writer object with delimiter.  Then use writerow() to send data in CSV file

KVS RO AGRA import csv with open(r'C:UserslenovoDesktoppython filesnew.csv','w') as wr: a=csv.writer(wr,delimiter=",") a.writerow(["Roll no","Name","Marks"]) a.writerow(["1","Rahul","85"]) a.writerow(["2","Priya","80"]) wr.close() Writing to CSV file

KVS RO AGRA Content of CSV file

KVS RO AGRA Reading from CSV file • import csv module • Use open() to open csv file, it will return file object. • Pass this file object to reader object. • Perform operation you want

KVS RO AGRA import csv with open(r'C:UserslenovoDesktoppython filesnew.csv',‘r') as rr: a=csv.reader(rr) for i in a: print(i) wr.close() Reading from CSV file

KVS RO AGRA THANK YOU & HAVE A NICE DAY UNDER THE GUIDANCE OF KVS RO AGRA VEDIO LESSON PREPARED BY: KIRTI GUPTA PGT(CS) KV NTPC DADRI

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