You can use one of the following three methods to add a header row to a pandas DataFrame:

#add header row when creating DataFrame
df = pd.DataFrame(data=[data_values],
                  columns=['col1', 'col2', 'col3'])

#add header row after creating DataFrame
df = pd.DataFrame(data=[data_values])
df.columns = ['A', 'B', 'C']

#add header row when importing CSV
df = pd.read_csv('data.csv', names=['A', 'B', 'C'])

The following examples show how to use each of these methods in practice.

Example 1: Add Header Row When Creating DataFrame

The following code shows how to add a header row when creating a pandas DataFrame:

import pandas as pd
import numpy as np

#add header row when creating DataFrame 
df = pd.DataFrame(data=np.random.randint(0, 100, (10, 3)),
                  columns =['A', 'B', 'C'])

#view DataFrame
df

	A	B	C
0	81	47	82
1	92	71	88
2	61	79	96
3	56	22	68
4	64	66	41
5	98	49	83
6	70	94	11
7	1	6	11
8	55	87	39
9	15	58	67

Example 2: Add Header Row After Creating DataFrame

The following code shows how to add a header row after creating a pandas DataFrame:

import pandas as pd
import numpy as np

#create DataFramedf = pd.DataFrame(data=np.random.randint(0, 100, (10, 3))) 
#add header row to DataFrame
df.columns = ['A', 'B', 'C']

#view DataFrame
df

	A	B	C
0	81	47	82
1	92	71	88
2	61	79	96
3	56	22	68
4	64	66	41
5	98	49	83
6	70	94	11
7	1	6	11
8	55	87	39
9	15	58	67

Example 3: Add Header Row When Importing DataFrame

The following code shows how to add a header row using the names argument when importing a pandas DataFrame from a CSV file:

import pandas as pd
import numpy as np

#import CSV file and specify header row names
df = pd.read_csv('data.csv', names=['A', 'B', 'C'])

#view DataFrame
df

	A	B	C
0	81	47	82
1	92	71	88
2	61	79	96
3	56	22	68
4	64	66	41
5	98	49	83
6	70	94	11
7	1	6	11
8	55	87	39
9	15	58	67