Sorting with Pandas does not return the desired output

Question

Say you have, for a network G, the following dict with (Node ID, number of links), and say you want to dump it to a Pandas DataFrame:

import pandas as pd
import networkx as nx

degree=pd.DataFrame({'Node ID':G.degree().keys(),'Degree':G.degree().values()})
degree=degree[['Node ID','Degree']] #re-order

You obtain this:

In[1]: degree.head(5)
Out[1]:
     Node ID  Degree
0    0        19
1    1        117
2    2        13
3    3        56
4    4        15

Now say you want to sort this DataFrame with respect to the Degree column, in descending order. If I do this

sort_degree=degree.sort_values(['Node ID', 'Degree'], ascending=[False, False], inplace=False)

I don't get what I want:

    Node ID  Degree
4   4        15
3   3        56
2   2        13
1   1        117
0   0        19

What's wrong?

Why don't you just sort by the 'Degree' column only? sort_degree=degree.sort_values('Degree', ascending=False) — EdChum
– EdChum, Commented Oct 20, 2016 at 15:09

EdChum · Accepted Answer · 2016-10-20 15:12:29Z

4

Seems to me you only need to sort by the Degree column:

In [156]:
sort_df = df.sort_values('Degree', ascending=False)
sort_df

Out[156]:
   Node ID  Degree
1        1     117
3        3      56
0        0      19
4        4      15
2        2      13

When you pass multiple columns then it will sort by those columns in the order they are passed, see the docs: http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.sort_values.html#pandas.DataFrame.sort_values

answered Oct 20, 2016 at 15:12

EdChum

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