Returning the actual index value of max & min values from a Pandas Dataframe column

Question

How do I print/return the index of a particular value?

movies_per_year = pd.DataFrame(movies_per_year)
movies_per_year.columns = ["count"]
print(movies_per_year)

        count
year       
1891      1
1893      1
1894      2
1895      2
1896      2
1898      5

Here, my index is the year. I want to return all the indexes where count is 1. Furthermore movies_per_year.max() returns 5. So, it should return 1898.

Possible duplicate of [Select rows from a DataFrame based on values in a column in pandas](https://stackoverflow.com/questions/17071871/select-rows-from-a-dataframe-based-on-values-in-a-column-in-pandas) — miravalls, May 22 '18 at 09:35

MaxU - stand with Ukraine · Accepted Answer · 2018-05-22T09:38:06.123

9

np.where() - returns positional indices of the elements that satisfy the given condition:

In [31]: np.where(df['count'] == 1)[0]
Out[31]: array([0, 1], dtype=int64)

or

In [35]: np.nonzero(df['count'] == 1)
Out[35]: (array([0, 1], dtype=int64),)

if you need real index values (labels) instead of their positions:

In [40]: df.index[df['count'] == 1]
Out[40]: Int64Index([1891, 1893], dtype='int64', name='year')

to find an index of a maximum element:

In [32]: df['count'].idxmax()
Out[32]: 1898

edited May 22 '18 at 09:38

answered May 22 '18 at 09:32

MaxU - stand with Ukraine

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Great! I just have one doubt, how do I print all the years that have count 1. For example, it should print 1891 and 1893. – Yash Ghorpade May 22 '18 at 09:36
2

try this to print all years that have count 1 `df.index[df['count'] == 1].tolist()` -- ignore this i see the answer was edited already to include it. – gyx-hh May 22 '18 at 09:39
@HamzaHaider, yes, we can use `Index.tolist()` method to convert index to Vanilla Python list. Thank you! – MaxU - stand with Ukraine May 22 '18 at 09:41

Returning the actual index value of max & min values from a Pandas Dataframe column

1 Answers1