Pandas Finding Index From Values In Column

Question

In using Python Pandas on a big dataset, how can I find the index based on the value in the column, in the same row?

For example, if I have this dataset...

           Column
Item 1     0
Item 2     20
Item 3     34
...
Item 1000  12

... and if I have this value 17 in one of the 1000 rows (excluding row 0) in the column, and I want to find out which one of the Item has this value 17 in the column in the same row, how can I do that?

For example, I want to find out what and where is this Item x indexed in the dataset as shown below...

           Column
Item x     17

... how can I do that with Pandas, using this value 17 as reference?

jezrael · Accepted Answer · 2016-11-18 09:55:56Z

12

Use boolean indexing:

df.index[df.Column == 17]

If need excluding row 0:

df1 = df.iloc[1:]
df1.index[df1.Column == 17]

Sample:

df = pd.DataFrame({'Column': {'Item 1': 0, 'Item 2': 20, 'Item 5': 12, 'Item 3': 34, 'Item 7': 17}})
print (df)
       Column
Item 1       0
Item 2      20
Item 3      34
Item 5      12
Item 7      17

print (df.index[df.Column == 17])
Index(['Item 7'], dtype='object')

print (df.index[df.Column == 17].tolist())
['Item 7']

df1 = df.iloc[1:]
print (df1)
        Column
Item 2      20
Item 3      34
Item 5      12
Item 7      17

print (df1.index[df1.Column == 17].tolist())
['Item 7']

edited Nov 18, 2016 at 9:55

answered Nov 18, 2016 at 9:50

jezrael

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4 Comments

Dorky Over a year ago

If this column has a name to it, like 'First Pillar', how will the code be? I tried your code with name change to the df like new[new.Column == 17] but it returns error.

jezrael Over a year ago

I think you need print (df[df['First Pillar'] == 17])

jezrael Over a year ago

You can test it with df = pd.DataFrame({'First Pillar': {'Item 1': 0, 'Item 2': 20, 'Item 5': 12, 'Item 3': 34, 'Item 7': 17}}) print (df)

obscuredbyclouds Over a year ago

this does not work for floating point column values ://

piRSquared · Accepted Answer · 2016-11-18 09:52:32Z

2

use query

df.query('Column == 17')

use index.tolist() to get the list of items

df.query('Column == 17').index.tolist()

answered Nov 18, 2016 at 9:52

piRSquared

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Comments

NL23codes · Accepted Answer · 2020-04-05 19:00:06Z

2

I tried one of the methods above and it did not work for me. I then put a bit more thought into it and realized I was making it more complicated than it needed to be. Here's the method I am using in my own program to get this functionality:

x = 17
df = pandas.DataFrame({'Item':[1,2,3,150],'Column':[0,20,34,17]})
response = df[df['Column'] == x].iloc[0]['Item']

print(response)

Output:

answered Apr 5, 2020 at 19:00

NL23codes

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