How do I change a single index value in pandas dataframe?

Question

energy.loc['Republic of Korea']

I want to change the value of index from ‘Republic of Korea’ to ‘South Korea’.
But the dataframe is too large and it is not possible to change every index value. How do I change only this single value?

Asked By: user517696

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Source

Answer 1

You want to do something like this:

as_list = df.index.tolist()
idx = as_list.index('Republic of Korea')
as_list[idx] = 'South Korea'
df.index = as_list

Basically, you get the index as a list, change that one element, and the replace the existing index.

Answered By: Batman

Answer 2

Here’s another idea based on set_value

df = df.reset_index()
df.drop('index', axis = 1, inplace=True)
index = df.index[df["Country"] == "Republic of Korea"]
df.set_value(index, "Country", "South Korea")
df = df.set_index("Country")
df["Country"] = df.index

Answered By: Andrea C

Answer 3

Here’s another good one, using replace on the column.

df.reset_index(inplace=True)
df.drop('index', axis = 1, inplace=True)
df["Country"].replace("Republic of Korea", value="South Korea", inplace=True)
df.set_index("Country", inplace=True)

Answered By: Andrea C

Answer 4

@EdChum’s solution looks good.
Here’s one using rename, which would replace all these values in the index.

energy.rename(index={'Republic of Korea':'South Korea'},inplace=True)

Here’s an example

>>> example = pd.DataFrame({'key1' : ['a','a','a','b','a','b'],
           'data1' : [1,2,2,3,nan,4],
           'data2' : list('abcdef')})
>>> example.set_index('key1',inplace=True)
>>> example
      data1 data2
key1             
a       1.0     a
a       2.0     b
a       2.0     c
b       3.0     d
a       NaN     e
b       4.0     f

>>> example.rename(index={'a':'c'}) # can also use inplace=True
      data1 data2
key1             
c       1.0     a
c       2.0     b
c       2.0     c
b       3.0     d
c       NaN     e
b       4.0     f

Answered By: ErnestScribbler

Answer 5

If you have MultiIndex DataFrame, do this:

# input DataFrame
import pandas as pd
t = pd.DataFrame(data={'i1':[0,0,0,0,1,1,1,1,2,2,2,2],
                       'i2':[0,1,2,3,0,1,2,3,0,1,2,3],
                       'x':[1.,2.,3.,4.,5.,6.,7.,8.,9.,10.,11.,12.]})
t.set_index(['i1','i2'], inplace=True)
t.sort_index(inplace=True)

# changes index level 'i1' values 0 to -1
t.rename(index={0:-1}, level='i1', inplace=True)

Answered By: S.V

Answer 6

Try This

df.rename(index={'Republic of Korea':'South Korea'},inplace=True)

Answered By: Abdul Rafay

Answer 7

This seems to work too:

energy.index.values[energy.index.tolist().index('Republic of Korea')] = 'South Korea'

No idea though whether this is recommended or discouraged.

Answered By: mpeli

Answer 8

We can use rename function to change row index or column name. Here is the example,

Suppose data frame is like given below,

       student_id     marks
index
  1        12          33
  2        23          98

To change index 1 to 5

we will use axis = 0 which is for row

df.rename({ 1 : 5 }, axis=0)

df refers to data frame variable. So, output will be like

       student_id     marks
index
  5        12          33
  2        23          98

To change column name

we will have to use axis = 1

df.rename({ "marks" : "student_marks" }, axis=1)

so, changed data frame is

       student_id     student_marks
index
  5        12              33
  2        23              98

Answered By: bhargav3vedi

How do I change a single index value in pandas dataframe?

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