Trim Pandas DataFrame based on values in list

Question

I'm trying to trim a DataFrame based on an input list, but I need to check if the items in the list are in some of the frame's columns.

(data below is random)

The frame I'd like to trim looks like this:

  UID           S1         S2  ElementHID  n1  n2  n3  n4
    0    88.340153 -88.340153         144   1   4   5   5  
    1    66.370153 -66.370153         144   4   1   5   4
    2    74.422513 -74.422513         144   2   7   3   6
    3    22.324573 -22.324573         144   1   9   8   1
    4    14.322413 -14.322413         144   3   4   6   3

Each row represents an element that can have up to 4 nodes.

I have a list of nodes (node_list) that I've filtered from another frame and I'd like to come in here and get which elements touch those nodes (nodes could be in n1, n2, n3, n4). There can be many elements joining on one node, so the 'n' columns have repeating data.

I'd like to avoid looping through the whole frame. I tried that but it took way too long. I'm hoping this can be done through Pandas.

The basic logic per row would be like [row if node in n1 or n2 or n3 or n4], where node is looping through the node_list

So far I've tried going through the columns individually, but I can't keep the columns straight after merging everything in frame_list.

frame_list = []
for n in range(1, 4):
    node = 'n' + str(n)
    if node in element_frame.columns:
        temp_frame = element_frame.merge(pd.DataFrame(node_list), left_on = node, right_on='uid', how = 'inner')
        frame_list.append(temp_frame)
    else:
        continue

I'm hoping there's an easier way!

Thanks,

khu

behzad.nouri · Accepted Answer · 2014-09-15 22:01:25Z

2

you can do something like:

>>> i = element_frame[['n1', 'n2', 'n3', 'n4']].isin(node_list).any(axis=1)

and then, i would be the boolean indexer:

>>> element_frame[i]

answered Sep 15, 2014 at 22:01

behzad.nouri

78.5k18 gold badges130 silver badges127 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Trim Pandas DataFrame based on values in list

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related