如何遍历Python中的CSV层次树？

Question

I'm trying to iterate through a hierarchy tree in a CSV file to do certain things with the items. The hierarchy is setup as follows: Hierarchy tree

Note that the actual items under the parent and child levels won't have words like parent/child in them, like this: Example tree

Now, I want to create two nested loops, with the 'outer' loop iterating through the parent levels and the 'inner' loop iterating through the child levels, and the bodies of each loop will do stuff with the information from each level of cell they deal with. To add additional clarification, each parent will have a variable number of children, so parent 1 could have 4, parent 2 could have 2, parent 3 could have 8, and so on. Can anyone help me with how I'd set these loops up to iterate through them the way I want?

Answer 1

I would have used pandas .

import pandas as pd

df = pd.read_csv(path_to_csv)

# Fill empty cells in parent column with the precedent value
df['parent'] = df.parent.fillna(method='ffill')

# Group cells with the same parent
df = df.groupby('parent').agg({'child': list})

print(df)
print(df.loc['Apple'])

This will end up with a table indexed by parent and their children grouped into a single cell in a list structure. You can next do whatever you want with the each list or even convert the pandas dataframe (=table) to anything else (list, dict...) that suits your case best.