How to sort a dataframe by values from a list

Question

I have a list with numbers:

[18, 22, 20]

and a dataframe:

Id                       | node_id
UC5E9-r42JlymhLPnDv2wHuA | 20
UCFqcNI0NaAA21NS9W3ExCRg | 18
UCrb6U1FuOP5EZ7n7LfOJMMQ | 22

list numbers map to node_id numbers. The order of the node_id numbers matters, they must be in the order of the list numbers.

So the dataframe is in the wrong order.

I need to sort the dataframe by the list values.

End result should be:

Id                       | node_id
UCFqcNI0NaAA21NS9W3ExCRg | 18    
UCrb6U1FuOP5EZ7n7LfOJMMQ | 22
UC5E9-r42JlymhLPnDv2wHuA | 20

How can I do this?

maybe this already has an answer here? stackoverflow.com/questions/6618515/… — Dylan
– Dylan, Commented Mar 2, 2020 at 13:59

jezrael · Accepted Answer · 2020-03-02 14:15:00Z

5

Use sorted Categorical, so you can use DataFrame.sort_values:

L = [18, 22, 20]
df['node_id'] = pd.Categorical(df['node_id'], ordered=True, categories=L)
df = df.sort_values('node_id')
print (df)
                         Id node_id
1  UCFqcNI0NaAA21NS9W3ExCRg      18
2  UCrb6U1FuOP5EZ7n7LfOJMMQ      22
0  UC5E9-r42JlymhLPnDv2wHuA      20

If want avoid Categorical column:

df = df.iloc[df['node_id'].map({v: k for k, v in enumerate(L)}).argsort()]

edited Mar 2, 2020 at 14:15

answered Mar 2, 2020 at 13:44

jezrael

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2 Comments

Vega Over a year ago

Thanks, any difference to the one liner from YOBEN_S?

jezrael Over a year ago

@Vega - Another solution is wrong. Because missing ordered=True

BENY · Accepted Answer · 2020-03-02 13:44:48Z

1

I will do

l=[18, 22, 20]
df=df.iloc[pd.Categorical(df.node_id, l).argsort()]
Out[79]: 
                         Id  node_id
1  UCFqcNI0NaAA21NS9W3ExCRg       18
2  UCrb6U1FuOP5EZ7n7LfOJMMQ       22
0  UC5E9-r42JlymhLPnDv2wHuA       20

answered Mar 2, 2020 at 13:44

BENY

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