Rename unnamed column pandas dataframe

Question

My csv file has no column name for the first column, and I want to rename it. Usually, I would do data.rename(columns={'oldname':'newname'}, inplace=True), but there is no name in the csv file, just ''.

Illboding

How was this csv generated? If it was exported from pandas then that sometimes indicatates that the first column was the index. In that case you can tell pandas this when reading it in pd.read_csv('file.csv', index_col=[0]) – Labarum

Answer 1

You can view the current dataframe using data.head()

if that returns 'Unnamed: 0' as the column title, you can rename it in the following way:

data.rename( columns={'Unnamed: 0':'new column name'}, inplace=True )

Landowner

my column has no name when I print the DataFrame it shows the column 0 only and i used this technique its not helping me, can you please suggest any other method to replace the name – Bladdernut

Answer 2

When you load the csv, use the option 'index_col' like

pd.read_csv('test.csv', index_col=0)

index_col : int or sequence or False, default None Column to use as the row labels of the DataFrame. If a sequence is given, a MultiIndex is used. If you have a malformed file with delimiters at the end of each line, you might consider index_col=False to force pandas to not use the first column as the index (row names)

http://pandas.pydata.org/pandas-docs/dev/generated/pandas.io.parsers.read_csv.html

Eutectoid

I dont think this solves the problem. I tried it and it did not – Devora

Answer 3

The solution can be improved as data.rename( columns={0 :'new column name'}, inplace=True ). There is no need to use 'Unnamed: 0', simply use the column number, which is 0 in this case and then supply the 'new column name'.

Professionalize

With Pandas 1.0.3, renaming columns by a dictionary with index keys doesn't seem to work. It only works for rows. – Neibart

In fact, I think it only works for rows because the actual DataFrame index uses sequential integers as row names. – Neibart

Answer 4

Try the below code,

df.columns = [‘A’, ‘B’, ‘C’, ‘D’]

Hairtail

The best and easiest solution! – Kephart

This works in this case but its not a good solution, If there is a change in the order of columns, this solution will mess up the columns. using df.rename and specifically mentioning the old & new column names is the most reliable way of doing it. – Terranceterrane

Answer 5

This should work:

data.rename( columns={0 :'Articles'}, inplace=True )

Rosenblast

Answer 6

It can be that the first column/row could not have a name, because it's an index and not a column/row. That's why you need to rename the index like this:

df.index.name = 'new_name'

Furculum

+1 bc I searched for a way to do this to no avail - really handy when all you want to do is copy/paste over to excel. come on python, everything should have a name by default! – Paperboard

I was searching for this since days, thank you! – Verdict

Answer 7

usually the blank column names are named based on their index

so for example lets say the 4 column is unnamed.

df.rename({'unnamed:3':'new_name'},inplace=True)

usually it is named like this since the indexing of columns start with zero.

Blavatsky

Answer 8

It has a name, the name is just '' (the empty string).

In [2]: df = pd.DataFrame({'': [1, 2]})

In [3]: df
Out[3]: 

0  1
1  2

In [4]: df.rename(columns={'': 'A'})
Out[4]: 
   A
0  1
1  2

Frightened

You need inplace=True to change df directly. df.rename(columns={'': 'A'}, inplace=True) – Cavalryman

i tried to use the inplace = True, and it returned the blank dataframe, not sure what's going on, is there any other solution?? – Bladdernut

just incase someone needed this: in pandas 0.23.4, I need to use .rename(columns={'Unnamed: 0': 'id'}) to rename the first unnamed column – Invention

Answer 9

As of 2024, this numeric index form works:

df.rename( columns={0 :'new_name'}, inplace=True )

while the string one doesn't:

df.rename( columns={'Unnamed: 0':'new_name'}, inplace=True )

Ga

I did data.rename( columns={'0':'new column name'}, inplace=True ) until I found this one that I cannot use column name as string, this is confusing for getting column renmae – Anikaanil

Answer 10

Another solution is to invoke the columns of the dataframe and use replace:

df.columns = df.columns.str.replace('Unnamed: 0','new_name')

Flautist