The max() function in a Polars Series is used to return the maximum (largest) value from the Series. Even if the Series contains just a single element, it still outputs a Series. The result is typically a float representing the maximum value found.
In this article, I will explain the syntax of the Polars Series max() function, its parameters, and how to use it to find the maximum value in a Series object.
Key Points –
- The
max()function returns the maximum (largest) value in a Series. - It works with numeric data types such as integers and floats.
- The function scans all elements in the Series to determine the highest value.
- The result is typically returned as a float, even if the Series contains integers.
- The return value is always wrapped in a Series object, not a plain scalar.
- Missing values (
null) are ignored by default when computing the maximum. - For string Series, it returns the lexicographically greatest string.
- Does not modify the original Series; it simply returns a value.
Polars Series max() Introduction
Let’s know the syntax of the series max() function.
# Syntax of max() function
Series.max() → PythonLiteral | None[source]
Parameters of the Polars Series max()
The following are the parameters of the polars Series max() function.
- The function returns a single value, specifically.
- A Python literal (like
int,float,str,bool, etc.) - Or
None(if the Series is empty)
- A Python literal (like
Return Value
This function returns a single value (like int, float, str, etc.). Or None if the Series is empty or contains only nulls.
Usage of Polars Series max() Function
The max() function in Polars Series is used to return the maximum (largest) value from the Series. This function gets the maximum value of the given object elements in Polars.
A Polars Series is a one-dimensional array that holds data of the same type, like integers, floats, or strings.
Now, let’s create a Polars series using a list of values and use the max() function.
import polars as pl
ser = pl.Series("numbers", [10, 25, 7, 42, 18])
print("Original Series:\n", ser)
Yields below output.
The max() function in Polars returns the largest value in the Series. It works with integer values the same way it does with floats or other comparable types.
# Get the maximum value
print("Maximum value:", ser.max())
# Find the maximum value
result = ser.max()
print("Maximum value:", result)
Yields below output.
Using max() with a Single Element Series
When a Polars Series contains just one element, the max() function returns that single value, as it serves as both the minimum and the maximum by default.
import polars as pl
# Create a Series with a single element
ser = pl.Series("single_value", [99])
print("Original Series:\n", ser)
# Find the maximum value
result = ser.max()
print("Maximum value in the Series:", result)
# Output:
# Original Series:
# shape: (1,)
# Series: 'single_value' [i64]
# [
# 99
# ]
# Maximum value in the Series: 99
Using max() with Floating-Point Numbers
The max() function in Polars works seamlessly with floating-point numbers, just like it does with integers. It evaluates the Series and returns the largest float value.
import polars as pl
ser = pl.Series("floats", [3.14, 2.71, 9.81, 1.41, 5.0])
print("Original Series:\n", ser)
# Find the maximum value
result = ser.max()
print("\nMaximum value:", result)
# Output:
# Original Series:
# shape: (5,)
# Series: 'floats' [f64]
# [
# 3.14
# 2.71
# 9.81
# 1.41
# 5.0
# ]
# Maximum value: 9.81
Using max() with Boolean Values
The Boolean values are treated numerically, False as 0 and True as 1. So when using max() on a Boolean Series, it returns True if there’s at least one True value present.
import polars as pl
# Create a Series with boolean values
ser = pl.Series("bools", [True, False, True, False])
print("Original Series:\n", ser)
# Find the maximum boolean value
result = ser.max()
print("Maximum value in the Series:", result)
# Output:
# Original Series:
# shape: (4,)
# Series: 'bools' [bool]
# [
# true
# false
# true
# false
# ]
# Maximum value in the Series: True
Using max() with Negative Numbers
The max() function in Polars also works with negative numbers. It returns the highest value in the Series, which, for negative values, means the number closest to zero.
import polars as pl
# Create a Series with negative integers
ser = pl.Series("negatives", [-12, -3, -45, -7, -19])
print("Original Series:\n", ser)
# Find the maximum (least negative) value
result = ser.max()
print("Maximum value in the Series:", result)
# Output:
# Original Series:
# shape: (5,)
# Series: 'negatives' [i64]
# [
# -12
# -3
# -45
# -7
# -19
# ]
# Maximum value in the Series: -3
Using max() with Missing Values
When the Series contains missing values (nulls), the max() function in Polars skips over them and returns the highest non-null value. For example, even with None entries present, the maximum here is 25.
import polars as pl
# Create a Series with some null values
ser = pl.Series("mixed", [10, None, 25, None, 18])
print("Original Series:\n", ser)
# Find the maximum value, skipping nulls
result = ser.max()
print("Maximum value in the Series:", result)
# Output:
# Original Series:
# shape: (5,)
# Series: 'mixed' [i64]
# [
# 10
# null
# 25
# null
# 18
# ]
# Maximum value in the Series: 25
Conclusion
In summary, the max() function in Polars is a straightforward yet effective way to find the highest value in a Series. It handles various data types, integers, floats, booleans, strings, and even nulls, with consistent and accurate results.
Happy Learning!!