Saving a Pandas DataFrame to a JSON string

Question

I realize that this may seem like a question that has already been asked here, but none of the solutions seem to work. I start out with a dictionary that looks something along the line of this:

{'2016-05-08': 1, '2016-05-09': nan, '2016-05-05': nan, '2016-05-06': nan, '2016-05-07': nan, '2016-05-11': nan, 'address': '<email address>, '2016-05-12': nan, '2016-05-10': nan}

I read this data into a pandas DataFrame, looking something like this:

address date1 date2 date3 date4 date5 date6 date7 <email> NaN NaN NaN 1 NaN NaN NaN

I then use the following methods to calculate the mean and standard deviation and add them to the DataFrame:

mean = pd.Series(df.mean(axis=1), index=df.index) std = pd.Series(df.std(axis=1), index=df.index) df = pd.concat([df, mean, std], axis=1)

When I print df, it looks as it should. However, when I used this method to write the DataFrame to a JSON string, df.to_json(<path to file>), it get the original dictionary in my JSON file. I want a JSON string of all the data with the standard deviation and mean included in the JSON data, how can I do this?

ivan7707 · Accepted Answer · 2016-06-22 20:52:21Z

2

If your summary columns give you the data you expect, add the columns to the dataframe.

Try

df['std'] = pd.Series(df.std(axis=1), index=df.index)

df['mean'] = pd.Series(df.mean(axis=1), index=df.index)

Then export to JSON.

Edit: ok, I see that you see it works with print df now sorry).

I was unable to reproduce your results. this is what I have:

import pandas as pd

d = {'2016-05-08': 1, '2016-05-09': float('nan'), '2016-05-05': float('nan'), '2016-05-06': float('nan'), '2016-05-07': float('nan'), '2016-05-11': float('nan'), 'address': '<email address>', '2016-05-12': float('nan'), '2016-05-10': float('nan')}

df = pd.DataFrame(d, index=[0])

mean = pd.Series(df.mean(axis=1), index=df.index)
std = pd.Series(df.std(axis=1), index=df.index)
df = pd.concat([df, mean, std], axis=1)

df.to_json('correctoutput.txt')

Here is the json with the output:

http://www.jsoneditoronline.org/?id=c0b29191d89fba8b593e29009af4f382

edited Jun 22, 2016 at 20:52

answered Jun 22, 2016 at 19:54

ivan7707

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5 Comments

BallsyWalnuts Over a year ago

Isn't that what the concat method does?

BallsyWalnuts Over a year ago

Doesn't change output

ivan7707 Over a year ago

@GrantSteiner, aside from the above edit, try this df.to_json() without the file to see if you get the right output.

BallsyWalnuts Over a year ago

Figured it out. It was an issue with other code in the program. Thank you for your help.

ivan7707 Over a year ago

@grant steiner glad I could help. Marking this as the answer would be appreciated.

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