Index has a special meaning in Pandas. It’s used to optimise specific operations and can be used in various methods such as merging / joining data. Therefore, make a choice:
- If it’s “just another column”, use
reset_indexand treat it as another column. - If it’s genuinely used for indexing, keep it as an index and use
df.index.
We can’t make this choice for you. It should be dependent on the structure of your underlying data and on how you intend to analyse your data.
For more information on use of a dataframe index, see:
- What is the performance impact of non-unique indexes in pandas?
- What is the point of indexing in pandas?