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frodocoder

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  • frodocoder
    Published:
    Python

    Writing JSON to a file in Python

    import json
import os
import uuid

filename = str(uuid.uuid4()) # create random file name

# JSON data to be written
jsonDict ={
    "firstname" : "John",
    "lastname" : "Doe",
    "age" : 30,
    "phonenumber" : "9976770500"
}

# write JSON to file
with open(filename, "w") as f:
    json.dump(jsonDict, f)

# read JSON string from file
f = open(filename, "r")
print(f.read())
f.close()
os.remove(filename)

# Output:
# {"firstname": "John", "lastname": "Doe", "age": 30, "phonenumber": "9976770500"}

    You can write JSON to a file using the json.dump() function from the JSON module combined with file handling in Python. In thisexample, we open a file in writing mode. If the file doesn't exist, it will be created. The json.dump() function converts the Python dictionary into a JSON string, which is then saved in the file.

    python
    file
    json
    write
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  • frodocoder
    Published:
    Python

    Read JSON file using Python

    import json
import uuid
 
jsonString = '{"firstname": "John", "lastname": "Doe"}'

# Create random file name and write json to file
filename = str(uuid.uuid4())

with open(filename, "w") as f:
    f.write(jsonString)

# Parse JSON string
# Deserializes json string into dict
print("Parse JSON string")
jsonDict = json.loads(jsonString)

# Iterating through the json
for key, value in jsonDict.items():
    print(key, value)

print()
#----------------------------------------------------#

print("Read JSON file")
f = open (filename, "r")
 
# Reading from file
jsonDict = json.loads(f.read())
 
# Iterating through the json
for key, value in jsonDict.items():
    print(key, value)
 
# Closing file
f.close()

# Output
# Parse JSON string
# firstname John
# lastname Doe
#
# Read JSON file
# firstname John
# lastname Doe

    This exampleillustrates how to read from both a string and a JSON file. Initially, we have a JSON string stored in the variable 'jsonString'. We convert this JSON string into a Python dictionary using json.loads() method, which is then stored in the variable 'jsonDict'. Next, we read a JSON string stored in a file using json.loads(). To achieve this, we first convert the JSON file into a string using file handling, similar to the previous example. Then, we convert it into a string using the read() function. The subsequent steps mirror those followed earlier, utilizing the json.loads() method.

    python
    read
    json
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  • frodocoder
    Published:
    Python

    Read a file line by line in Python

    import os
import uuid

filename = str(uuid.uuid4()) # create random file name
wLines = ["First line\n", "Second line\n", "Third line\n"]

# writing lines to file
f = open(filename, 'w')
f.writelines(wLines)
f.close()

#--------------------------------------------------------#

print("-----Read lines using 'readlines' method-----")
f = open(filename, 'r')
rLines = f.readlines()

for lineNumber, line in enumerate(rLines, 1):
	print("Line {}: {}".format(lineNumber, line.strip()))

#--------------------------------------------------------#

print("-----Read lines using 'readline' method-----")
f = open(filename, 'r')
lineNumber = 1
 
while True:
    lineNumber += 1
 
    # Get next line from file
    line = f.readline()
 
    # if line is empty
    # end of file is reached
    if not line:
        break
    print("Line {}: {}".format(lineNumber, line.strip()))
 
f.close()

#--------------------------------------------------------#

print("-----Read lines via file object iteration-----")
f = open(filename, 'r')

for lineNumber, line in enumerate(f, 1):
    print("Line {}: {}".format(lineNumber, line.strip()))

#--------------------------------------------------------#

print("-----Read lines via file contex manager-----")
with open(filename, "r") as f:
    for lineNumber, line in enumerate(f, 1):
        print("Line {}: {}".format(lineNumber, line.strip()))

os.remove(filename) # remove file

# Output example:

# Read lines using 'readlines' method
# Line 1: First line
# Line 2: Second line
# Line 3: Third line

    Here's an example of reading from a file line by line in Python.

    python
    file
    read
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