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Python Read and Write File (JSON, XML, CSV, Text) - Sample Code


Python Read and Write File (JSON, XML, CSV, Text) - Sample Code. In this post , we will see - How To Read & Write Various File Formats in Python.  

1. JSON Files - Read and Write from Python :

Write JSON Objects into Python :


\# Converting the JSON objects to print in Python
import json
\# some JSON: x =  '{ "city":"Washington", "population":300000, "country":"US"}'
\# parse x: y = json.loads(x)
\# the result is a Python dictionary: print(y\["city"\])

Converting Python Objects to JSON :


import json
\# Python Dictionary object: x = {
  "city":"Washington", 
  "population":300000, 
  "country":"US"
}

\# convert into JSON: y = json.dumps(x)

\# the result is a JSON string: print(y)
  Read JSON File :


import json

with open('<LOCATION/file.json') as f:
data = json.loads(f)

print(data)

# To Pretty Print
print(json.dumps(data, indent = 4, sort\_keys=True))
Write JSON Data to a File :


import json

data\_dict = {
  "city":"Washington", 
  "population":300000, 
  "country":"US"
}

with open('file.txt', 'w') as json\_file:
json.dump(data\_dict, json\_file)
 

2. XML Files - Read and Write from Python :

Consider an XML file with below sample contents - TEST.xml


<nodedetails>
  <name>SERVER-1</name>
  <description/>
  <numExecutors>SOME\_NO\_XX</numExecutors>
  <mode>SOME\_MODE\_XX</mode>
  <launcher class="xxxxx" plugin="xxxxx">
    <hostname>128.0.0.1</hostname>
    <portno>9900</portno>
    <credentialsId>TESTID</credentialsId>
    <maxNumRetries>3</maxNumRetries>
  </launcher>
  <label>somelabel</label>
</nodedetails>
Read from the XML File using ElementTree :


import xml.etree.ElementTree as ET
tree = ET.parse("TEST.xml")
root = tree.getroot()

for item in root.iter('nodedetails'):
    for name in item.iter("name"):
        print name.text
    for portno in item.iter("portno"):
        print portno.text
  Read from any XML File using Beautifulsoup :


from bs4 import BeautifulSoup

with open('ANYXMLFILE.xml', 'r') as f: 
data = f.read()

# Beautifulsoup will parse the data 
All\_data = BeautifulSoup(data, "xml")

# Finding all instances of any tag  
tag\_data = All\_data.find\_all('<ANY\_TAG\_NAME>')
print(tag\_data)
  Writing an XML File using ElementTree :


import xml.etree.ElementTree as ET

# Parent (root) tag 
data1 = ET.Element('parents')

# Adding a subtag named \`children\`  inside our root tag "parents"
data2 = ET.SubElement(data1, 'children')

# Adding subtags under the \`children\` subtag 
grandChild1 = ET.SubElement(data2, 'E4') 
grandChild2 = ET.SubElement(data2, 'D4')

# Adding attributes to the tags under 
# \`items\` 
grandChild1.set('card', 'Credit\_Card') 
grandChild2.set('card', 'Debit\_Card')

# Adding text to grandchildren subtags
grandChild1.text = "Only Credit Cards Accepted"
grandChild2.text = "Only Debit Cards Accepted"

# Convert xml data to byte object to write into filestream 
data\_xml = ET.tostring(data1)

# Write to a file with operation mode \`wb\` (write + binary) 
with open("OUTPUT.xml", "wb") as f: 
f.write(data\_xml)
  Writing to an XML using Beautifulsoup : (Assuming you are modifying the contents of an input XML file and Writing the modifying XML output to Another XML file)


#Open file
soup = BeautifulSoup(open('INPUT.xml'),'xml')

modified\_xml\_content = <MODIFIED XML content as per Business Logic>

#Write to a file
f = open('OUTPUT.xml', "w")
f.write(str(modified\_xml\_content))
f.close()
 

3. CSV Files - Read and Write from Python :

Read from CSV File using Native Python Lib :


import csv
with open('TESTFILE.csv') as inputfile:
data = csv.reader(inputfile, delimiter=',')
Read from CSV File using Pandas Lib :


import pandas as pd
data = pd.read\_csv('TESTFILE.csv')
# Display first 10 Lines of data
data.head(10)
Write to a CSV File using Native Python lib :


import csv

data = <DATA\_TO\_BE\_WRITTEN>

writer = csv.writer(open("OUTPUTFILE", 'w'))
for row in data:
   writer.writerow(row)
 


with open(filename, 'w', newline='') as testfile:
   wr = csv.writer(testfile, quoting=csv.QUOTE\_ALL)
   wr.writerow(list)
 

4. Text Files - Read and Write from Python :

Read from a Text File :


data = open ("<File\_Name>","Read\_Access\_Mode")

# OPEN THE FILE FOR READ ONLY
fileA = open("TESTFILE.txt","r")     
fileA.close() 

# Read data bytes in form of a string. If 'n" bytes not specified, it reads the entire file.
fileA.read(\[n\])

# Read a line of the file and returns in form of a string
fileA.readline(\[n\])

# Reads all the lines and return each line a string element in a list.
fileA.readlines()
  Write into the Text File :


\# OPEN THE FILE FOR READ & WRITE BOTH
fileB = open(r"TESTFILE.txt","w+") 

L = \["data line 1 \\n","data line 2 \\n","data line 3 \\n"\] 

fileB.writelines(L) 
fileB.close()
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