Converting Multiple Dictionary Rows to a Pandas DataFrame
Introduction
In this article, we’ll learn how to convert multiple dictionary rows from a CSV file to a Pandas DataFrame. This is especially useful when you have a script that processes commands from multiple rows in the CSV file and needs to be integrated with other parts of your system.
Let’s say you have a script that reads command parameters from a CSV file using a “for” loop:
data = pd.read_csv('command parameters.csv')
df = pd.DataFrame(data)
However, each row in the CSV file represents an individual command parameter. If your data contains multiple dictionary rows, you’ll need to convert them to a single DataFrame.
To achieve this, we can use the “apply” method and apply it to each row of the dictionary in turn. Here is an example:
import pandas as pd
Define a function that converts a single dictionary row to a Pandas Series (i.e. a column)def dict_to_series(row):
return pd.Series([dict[row].get('value', None)], index=['key'])
Apply this function to each row of the DataFramedf['orderparameter'] = df.apply(dict_to_series, axis=1)
print(df)
This will create a new column called “orderparameter” in your original DataFrame. The value of each cell is a Pandas Series containing a value from each row of the dictionary.
Here’s what happens when we call the dict_to_series
function on each row of the DataFrame:
df.apply(dict_to_series, axis=1)
applies this function to each row (index 0) in turn. Theaxis=1
parameter tells Pandas that we want to apply the function element-wise along the rows.
axis=1
means that we treat each row of the dictionary as an individual column in our DataFrame.
The result is a new Series column called “orderparameter”, where each cell contains a value from the corresponding dictionary row. If there are missing values (i.e. no “value” key in the dictionary), they will be represented as “None”.
Suppose your CSV file has two rows:
{'id': 1, 'quantity': 10, 'price': 100},
{'id': 2, 'quantity': 20, 'price': 200}
When you run the script that reads these rows into a DataFrame, it creates a new column called “orderparameter” with values like this:
| main | quantity | price | orderparameter |
| --- | --- | --- | --- |
| 1 | 10 | 100 | [10.0] |
| 2 | 20 | 200 | [20.0] |
Note that the values in each cell are lists, as expected.
By following this approach, you can easily convert multiple rows of dictionaries into a Pandas DataFrame ready for further processing or analysis.