Get row-index values of Pandas DataFrame as list?
Question:
I’m probably using poor search terms when trying to find this answer. Right now, before indexing a DataFrame, I’m getting a list of values in a column this way…
list = list(df['column'])
…then I’ll set_index on the column. This seems like a wasted step. When trying the above on an index, I get a key error.
How can I grab the values in an index (both single and multi) and put them in a list or a list of tuples?
Answers:
To get the index values as a list/list of tuples for Index/MultiIndex do:
df.index.values.tolist() # an ndarray method, you probably shouldn't depend on this
or
list(df.index.values) # this will always work in pandas
If you’re only getting these to manually pass into df.set_index(), that’s unnecessary. Just directly do df.set_index['your_col_name', drop=False], already.
It’s very rare in pandas that you need to get an index as a Python list (unless you’re doing something pretty funky, or else passing them back to NumPy), so if you’re doing this a lot, it’s a code smell that you’re doing something wrong.
I’m probably using poor search terms when trying to find this answer. Right now, before indexing a DataFrame, I’m getting a list of values in a column this way…
list = list(df['column'])
…then I’ll set_index on the column. This seems like a wasted step. When trying the above on an index, I get a key error.
How can I grab the values in an index (both single and multi) and put them in a list or a list of tuples?
To get the index values as a list/list of tuples for Index/MultiIndex do:
df.index.values.tolist() # an ndarray method, you probably shouldn't depend on this
or
list(df.index.values) # this will always work in pandas
If you’re only getting these to manually pass into df.set_index(), that’s unnecessary. Just directly do df.set_index['your_col_name', drop=False], already.
It’s very rare in pandas that you need to get an index as a Python list (unless you’re doing something pretty funky, or else passing them back to NumPy), so if you’re doing this a lot, it’s a code smell that you’re doing something wrong.