Pandas Get First Column of DataFrame as Series?

We can get the first column of pandas DataFrame as a Series by using iloc[], columns[], and head() function. In this article, I will explain how to get the first columns of DataFrame as a series with several examples.

Key Points –

Use the .iloc method to access the first column by index position.
You can retrieve the first column using positional indexing, such as df.iloc[:, 0].
The .iloc property allows precise row and column selection by integer-location, making it straightforward to get the first column.
If you know the column name, it can be directly accessed with .loc or by calling df['column_name'].
Extracting a single column from a DataFrame returns a Series, not a DataFrame.
Using .columns[0] with df[] allows retrieval of the first column by its name dynamically.

Quick Examples of Getting First Column as a Series

If you are in a hurry below are some quick examples of getting the first column as a Series.


# Quick examples of getting first column as a series

# Example 1: Use Dataframe.iloc[] 
# To get first column as a series
df2 = df.iloc[:, 0]

# Example 2: Use columns[] 
# To get first column as a series
df2 = df[df.columns[0]]

# Example 3: Use column name 
# To get first column as a series
df2 = df.Courses

# Example 4: Use head() function 
# To get first column as a series
df2 = df.T.head(1).T

Create Pandas DataFrame

Let's create a Pandas DataFrame from a Python dictionary in which keys are 'Courses', 'Fee', 'Duration' and 'Discount‘, and values are taken as a list of corresponding key values.


import pandas as pd
technologies = {
    'Courses':["Spark","PySpark","Hadoop","Python","PySpark"],
    'Fee' :[20000,25000,26000,22000,24000],
    'Duration':['30days','40days','35days','40days','60days'],
    'Discount':[1000,2300,1200,2500,2000]
              }
df = pd.DataFrame(technologies)
print("Create DataFrame:\n", df)

Yields below output.

Get the First Column as a Series

In pandas, each column is represented as a Series hence it is very easy to get the first column of pandas DataFrame as a Series by using the iloc[] property. Use df.iloc[:,0] to get the first column as a Series. For example.


# Get first column as a series
df2 = df.iloc[:, 0]
print("After getting the first column of DataFrame as a series:\n", df2)

Yields below output.

Use df[] to Get the First Column as a Series

When we use df[df.columns[i]] function for extracting the first column of DataFrame, it will return the column based on the label associated with the index. Here, df.columns[0] returns the label of the first column of DataFrame, and df['label'] returns the column as a Series.


# Get first column as a series
df2 = df[df.columns[0]]
print("After getting the first column of DataFrame as a series:\n", df2)

Yields the same output as above. We can also use the column name to extract the first column as a series. For examples.


# Use column name 
# To get first column as a series
df2 = df.Courses
print("After getting the first column of DataFrame as a series:\n", df2)

Yields the same output as above.

Use head() to Get First Column of Pandas DataFrame

We can also use df.T.head(1).T to get the first column of pandas DataFrame as a Series.


# Use head() function 
# To get first column as a series
df2 = df.T.head(1).T
print("After getting the first column of DataFrame as a series:\n", df2)

Yields below output.


# Output:
# After getting the first column of DataFrame as a series:
   Courses
0    Spark
1  PySpark
2   Hadoop
3   Python
4  PySpark

Complete Example


import pandas as pd
technologies = {
    'Courses':["Spark","PySpark","Hadoop","Python","PySpark"],
    'Fee' :[20000,25000,26000,22000,24000],
    'Duration':['30days','40days','35days','40days','60days'],
    'Discount':[1000,2300,1200,2500,2000]
              }
df = pd.DataFrame(technologies)
print(df)

# Use DataFrame.iloc[] 
# To get first column as a series
df2 = df.iloc[:, 0]
print(df2)

# Use columns[] 
# To get first column as a series
df2 = df[df.columns[0]]
print(df2)

# Use column name 
# To get first column as a series
df2 = df.Courses
print(df2)

# Use head() function 
# To get first column as a series
df2 = df.T.head(1).T
print(df2)

Frequently Asked Questions of Get First Column of DataFrame as Series

To get the first column as a Series, you can use square bracket indexing with the column name or the .iloc method. For example, df_first_column = df['ColumnName'] or
df_first_column = df.iloc[:, 0]

If you don't know the name of the first column, you can use the .iloc method with the numeric index. For example, df_first_column = df.iloc[:, 0]

You can use the .iloc method with the numeric index to get the first column. For example, df_first_column = df.iloc[:, 0]

If you want to specify the data type of the resulting Series, you can use the .astype() method. For example, df_first_column = df['ColumnName'].astype('desired_dtype')

Conclusion

In this article, I have explained how to get the first column of pandas DataFrame as a Series by using DataFrame.iloc[], DataFrame.columns[], and head() function with examples.

Happy Learning !!

References

https://pandas.pydata.org/docs/reference/api/pandas.Series.html

Pandas Get First Column of DataFrame as Series?

Quick Examples of Getting First Column as a Series

Create Pandas DataFrame

Get the First Column as a Series

Use df[] to Get the First Column as a Series

Use head() to Get First Column of Pandas DataFrame

Complete Example

Frequently Asked Questions of Get First Column of DataFrame as Series

Conclusion

Related Articles

References