将CSV转换为JSON时未在python中获得预期的输出

Question

I have an excel file in which data is saved in csv format in such a way.This data is present in the excel file as shown below,under column A (The CSV File is generated by LabView Software code which i have written to generate data).I have also attached an image of the csv file for reference at the end of my question.

RPM,Load Current,Battery Output,Power Capacity
1200,30,12,37
1600,88,18,55

I want to create a Json file in such format

{  
   "power_capacity_data" :
   {
   "rpm" : ["1200","1600"],
   "load_curr" : ["30","88"],
   "batt_output" : ["12","18"],
   "power_cap" : ["37","55"]
   }
 }

This is my code

import csv
import json 

def main():

    #created a dictionary so that i can append data to it afterwards

    power_data = {"rpm":[],"load_curr":[],"batt_output":[],"power_cap":[]}

    with open('power1.lvm') as f:
        reader = csv.reader(f)

        #trying to append the data of column "RPM" to dictionary
       rowcount = 0
       for row in reader:   
           if rowcount == 0:
               #trying to skip the first row
               rowcount = rowcount + 1 
           else:
               power_data['rpm'].append(row[0])
               print(row)

        json_report = {}        
        json_report['pwr_capacity_data'] = power_data
        with open('LVMJSON', "w") as f1:
            f1.write(json.dumps(json_report, sort_keys=False, indent=4, separators=(',', ': '),encoding="utf-8",ensure_ascii=False))
            f1.close()


 if __name__ == "__main__":
     main()

The output json file that i am getting is this:(please ignore the print(row) statement in my code)

{
"pwr_capacity_data": 
  {
    "load_curr": [],
    "rpm": [
        "1200,30,12.62,37.88",
        "1600,88,18.62,55.88"
    ],
    "batt_output": [],
    "power_cap": []
  } 
}

The whole row is getting saved in the list,but I just want the values under the column RPM to be saved .Can someone help me out with what I may be doing wrong.Thanks in advance. I have attached an image of csv file to just in case it helps

Answer 1

You could use Python's defaultdict to make it a bit easier. Also a dictionary to map all your header values.

from collections import defaultdict    
import csv
import json

power_data = defaultdict(list)

header_mappings = {
    'RPM' : 'rpm',
    'Load Current' : 'load_curr',
    'Battery Output' : 'batt_output',
    'Power Capacity' : 'power_cap'}

with open('power1.lvm', newline='') as f_input:
    csv_input = csv.DictReader(f_input)

    for row in csv_input:
        for key, value in row.items():
            power_data[header_mappings[key]].append(value)

with open('LVMJSON.json', 'w') as f_output:            
    json.dump({'power_capacity_data' : power_data}, f_output, indent=2)

Giving you an output JSON file looking like:

{
  "power_capacity_data": {
    "batt_output": [
      "12",
      "18"
    ],
    "power_cap": [
      "37",
      "55"
    ],
    "load_curr": [
      "30",
      "88"
    ],
    "rpm": [
      "1200",
      "1600"
    ]
  }
}