Yelp数据集JSON转CSV脚本无输出问题排查求助（Python3）

Let's walk through the issues with your script and get it generating CSV files properly, plus answer your questions about file paths and parameters.

1. The Critical Reason No CSV is Being Generated #

Your script's main execution block isn't running at all! You have a typo in the entry point check:

if name == 'main':  # Wrong

This should be Python's standard double-underscore syntax:

if __name__ == '__main__':  # Correct

Without the underscores, the code that parses arguments, generates the CSV filename, and runs the conversion never executes—so the script runs but does nothing.

2. Other Script Syntax & Logic Fixes #

Broken Import Statement #

Your first line tries to import multiple modules in one line, which is invalid. Split them into separate lines:

import argparse
import collections
import csv
import json

Encoding Consistency #

In get_superset_of_column_names_from_file, you open the JSON file without specifying encoding="utf8"—this can cause encoding errors on Windows. Update that function:

def get_superset_of_column_names_from_file(json_file_path):
    column_names = set()
    with open(json_file_path, encoding="utf8") as fin:  # Added encoding
        for line in fin:
            line_contents = json.loads(line)
            column_names.update( set(get_column_names(line_contents).keys()) )
    return column_names

Clean Up String Handling in CSV Rows #

Your get_row function encodes strings to bytes, which will write b'your text' into the CSV (not what you want). Replace that logic to write raw strings (and handle newlines to avoid CSV formatting issues):

def get_row(line_contents, column_names):
    row = []
    for column_name in column_names:
        line_value = get_nested_value(line_contents, column_name)
        if isinstance(line_value, str):
            # Replace newlines to prevent breaking CSV rows
            row.append(line_value.replace('\n', ' ').replace('\r', ''))
        elif line_value is not None:
            row.append(str(line_value))
        else:
            row.append('')
    return row

3. File Path & Parameter Questions #

Current Behavior (No Manual Path Needed) #

Right now, your script:

• Takes the input JSON filename as a positional argument
• Automatically generates the CSV filename by replacing .json with .csv (e.g., review.json → review.csv)
• Saves the CSV in your current working directory (the folder you're in when running the command)

How to Manually Specify Output Path/Name #

If you want to control where the CSV is saved, add an optional argument to the parser. Update the __main__ block like this:

if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='Convert Yelp data from JSON format to CSV.',
    )
    parser.add_argument(
        'json_file', type=str,
        help='The json file to convert (can be a full path or relative path).',
    )
    # Add optional output argument
    parser.add_argument(
        '--output', '-o', type=str,
        help='Optional: Full or relative path for the output CSV file. If not provided, uses input filename with .csv extension.',
        default=None
    )
    args = parser.parse_args()
    
    json_file = args.json_file
    # Use specified output path if provided, else auto-generate
    if args.output:
        csv_file = args.output
    else:
        csv_file = '{0}.csv'.format(json_file.split('.json')[0])
    
    column_names = get_superset_of_column_names_from_file(json_file)
    read_and_write_file(json_file, csv_file, column_names)

Now you can run it with a custom output path like:

C:\Users\AppData\Local\Programs\Python\Python36-32>python.exe json_to_csv_converter.py review.json -o C:\MyData\yelp_reviews.csv

Correct Command Execution Tips #

• If your review.json isn't in the same folder as your script (or the folder you're running the command from), use the full path to the JSON file:

  python.exe json_to_csv_converter.py C:\Path\To\Your\Data\review.json
  

• Alternatively, navigate to the JSON file's folder first, then run the script with the relative path:

  cd C:\Path\To\Your\Data
  C:\Users\AppData\Local\Programs\Python\Python36-32\python.exe C:\Path\To\Your\Script\json_to_csv_converter.py review.json
  

Full Corrected Script #

import argparse
import collections
import csv
import json

def read_and_write_file(json_file_path, csv_file_path, column_names):
    with open(csv_file_path, 'w+', newline='', encoding="utf8") as fout:  # Added newline='' and encoding
        csv_file = csv.writer(fout)
        csv_file.writerow(list(column_names))
        with open(json_file_path, encoding="utf8") as fin:
            for line in fin:
                line_contents = json.loads(line)
                csv_file.writerow(get_row(line_contents, column_names))

def get_superset_of_column_names_from_file(json_file_path):
    column_names = set()
    with open(json_file_path, encoding="utf8") as fin:
        for line in fin:
            line_contents = json.loads(line)
            column_names.update( set(get_column_names(line_contents).keys()) )
    return column_names

def get_column_names(line_contents, parent_key=''):
    column_names = []
    for k, v in line_contents.items():
        column_name = "{0}.{1}".format(parent_key, k) if parent_key else k
        if isinstance(v, collections.MutableMapping):
            column_names.extend( get_column_names(v, column_name).items() )
        else:
            column_names.append((column_name, v))
    return dict(column_names)

def get_nested_value(d, key):
    if '.' not in key:
        if key not in d:
            return None
        return d[key]
    base_key, sub_key = key.split('.', 1)
    if base_key not in d:
        return None
    sub_dict = d[base_key]
    return get_nested_value(sub_dict, sub_key)

def get_row(line_contents, column_names):
    row = []
    for column_name in column_names:
        line_value = get_nested_value(line_contents, column_name)
        if isinstance(line_value, str):
            row.append(line_value.replace('\n', ' ').replace('\r', ''))
        elif line_value is not None:
            row.append(str(line_value))
        else:
            row.append('')
    return row

if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='Convert Yelp data from JSON format to CSV.',
    )
    parser.add_argument(
        'json_file', type=str,
        help='The json file to convert (can be a full path or relative path).',
    )
    parser.add_argument(
        '--output', '-o', type=str,
        help='Optional: Full or relative path for the output CSV file. If not provided, uses input filename with .csv extension.',
        default=None
    )
    args = parser.parse_args()
    
    json_file = args.json_file
    if args.output:
        csv_file = args.output
    else:
        csv_file = '{0}.csv'.format(json_file.split('.json')[0])
    
    column_names = get_superset_of_column_names_from_file(json_file)
    read_and_write_file(json_file, csv_file, column_names)

内容的提问来源于stack exchange，提问作者carmem