select column value based on index name in Pandas DataFrame

Question

I have a DataFrame named score_df having one column named Score and there are names of indices as following

           Score
year       0.029827
yesterday  0.029827
you        0.089482
zeros      0.029827
zones      0.029827

I have another df having a column named df['keywords'] having various keywords. I need to iterate over this column and search in indices of score_df and if index matches with keyword I need to append it's Score value in a list. I am using following code.

for key_w in df['keyword'].to_list():
    result = score_df.loc[key_w, :]

But it is giving KeyError: 'keyword value'. Can some help me how can I select required value? Thank you

error is for print ( df['keyword']) ?

jezrael
– jezrael

2021-01-19 07:09:35 +00:00
Commented Jan 19, 2021 at 7:09 — jezrael
– jezrael, Commented Jan 19, 2021 at 7:09

jezrael · Accepted Answer · 2021-01-19 07:21:45Z

2

I think you need DataFrame.merge with default inner join:

print (score_df)
              Score
year       0.029827
yesterday  0.029827
you        0.089482
zeros      0.029827
zones      0.029827

print (df)
     keyword
0      aaaaa
1  yesterday
2        you

print (score_df.merge(df, left_index=True, right_on='keyword'))
      Score    keyword
1  0.029827  yesterday
2  0.089482        you

L = score_df.merge(df, left_index=True, right_on='keyword')['Score'].tolist()
print (L)
[0.029827, 0.089482]

Or select index by column keyword in Index.isin and boolean indexing:

L = score_df.loc[score_df.index.isin(df['keyword']), 'Score'].tolist()

edited Jan 19, 2021 at 7:21

answered Jan 19, 2021 at 7:11

jezrael

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Comments

Mykola Zotko · Accepted Answer · 2021-01-19 08:12:11Z

0

You can use the method filter. For example:

df1

   col
A    0
B    1
C    2

df2

  keys
0    A
1    B
2    Z


df1.filter(df2['keys'], axis=0)

Output:

   col
A    0
B    1

To convert it to list use tolist()

edited Jan 19, 2021 at 8:12

answered Jan 19, 2021 at 7:51

Mykola Zotko

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