Reading/Writing out a dictionary to csv file in python

Question

Pretty new to python, and the documentation for csv files is a bit confusing.

I have a dictionary that looks like the following:

key1: (value1, value2)

key2: (value1, value2)

key3: (value1, value2)
....

I would like to write these out to a csv file in the format where each line contains the key, followed by the two values.

I would also like to be able to read them back into a dictionary from the file at a later date.

Answer 1

I highly recommend Pandas for this.

Convert to Pandas DataFrame:

import pandas as pd

d = {
    'a': (1, 101),
    'b': (2, 202),
    'c': (3, 303)
}
df = pd.DataFrame.from_dict(d, orient="index")

Create a CSV file:

df.to_csv("data.csv")

Read the CSV file back as a DataFrame:

df = pd.read_csv("data.csv", index_col=0)

Convert the DataFrame back to the original dictionary format:

d = df.to_dict("split")
d = dict(zip(d["index"], d["data"]))

EDIT: Since you mention that your goal to use the output file in Excel, Pandas to_excel() and read_excel() might be more useful to you since they better-preserve the content between conversions. Also, you might want skip Excel altogether and use the standard Python scientific stack.

Answer 2

I would use pandas, it can be done in one line:

import pandas as pd

dic = {'key1':['v1','v2'], 'key2':['vv','gg']}

pd.DataFrame(dic).T.reset_index().to_csv('myfile.csv', header=False, index=False)