Data file handling in python binary & csv files

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BINARY FILES
&
CSV(COMMA SEPARATED VALUES) FILES

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BINARY FILES

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CREATING BINARY FILES

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

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READING BINARY FILES TROUGH PROGRAM
CONTENT OF BINARY
FILE

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PICKELING AND UNPICKLING USING PICKLE MODULE

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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.

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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

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pickle.dump() Method

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

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

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pickle.load() Method

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

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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()

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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()

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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()

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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()

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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()

20. 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

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COMMA SEPARATED VALUE(CSV
Files)

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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

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• 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?

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• 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

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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.

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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

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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

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Content of CSV file

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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

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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

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