Converting pandas DataFrame to JSON array gives "only size-1 arrays can be converted to Python scalars" error

Question

I'm trying to read a CSV file and convert its contents to a JSON array, but I'm getting the error: "only size-1 arrays can be converted to Python scalars"

The csv file contents are

   4.4.4.4
   5.5.5.5

My code is below

import numpy as np
import pandas as pd
df1 = pd.read_csv('/Users/Documents/datasetfiles/test123.csv', header=None)

df1.head(5)
    0
0   4.4.4.4
1   5.5.5.5


df_to_array = np.array(df1) 
app_json = json.dumps(df_to_array,default=int)

Error i am getting

TypeError: only size-1 arrays can be converted to Python scalars

I need output as

["4.4.4.4", "5.5.5.5", "3.3.3.3"]

What I've tried:

Using np.array(df1) to convert the DataFrame to a numpy array

Using json.dumps() with default=int parameter

Question: Why am I getting this error, and what's the correct way to convert my DataFrame to a JSON array of strings?

Also in your code you are importing numpy as np and pd as well... — user269867
– user269867, Commented Sep 12, 2022 at 3:26
@bn_ln list gives values in single quotes ,I need in double quotes as json array — pythonNinja
– pythonNinja, Commented Sep 12, 2022 at 3:32
ok thanks @bn_ln ,i added as like this and it worked import json df_to_array = list(df1[0]) app_json = json.dumps(df_to_array,default=int) print(app_json) ["4.4.4.4", "5.5.5.5"] — pythonNinja
– pythonNinja, Commented Sep 12, 2022 at 3:33

halfdanr · Accepted Answer · 2022-09-12 03:40:40Z

1

As other answers mentioned, just use list: json.dumps(list(df[0]))

FYI, the data shape is your problem:

if you absolutely must use numpy, then transpose the array first:

json.dumps(list(df_to_array.transpose()[0]))

answered Sep 12, 2022 at 3:40

halfdanr

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Comments

BeRT2me · Accepted Answer · 2022-09-12 04:14:02Z

1

Given test.csv:

4.4.4.4
5.5.5.5

Doing:

import json

with open('test.csv') as f:
    data = f.read().splitlines()

print(data)
print(json.dumps(data))

Output:

['4.4.4.4', '5.5.5.5']
["4.4.4.4", "5.5.5.5"]

You're overcomplicating things using pandas is this is all you want to do~

answered Sep 12, 2022 at 4:14

BeRT2me

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pythonNinja · Accepted Answer · 2022-09-12 03:36:36Z

0

import json
import pandas as pd
df1 = pd.read_csv('/Users/Documents/datasetfiles/test123.csv', header=None)

df1.head(5)
    0
0   4.4.4.4
1   5.5.5.5


df_to_array = list(df1[0]) 
app_json = json.dumps(df_to_array,default=int)

print(app_json)
["4.4.4.4", "5.5.5.5", "3.3.3.3"]

answered Sep 12, 2022 at 3:36

pythonNinja

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