diff --git a/content/numpy/concepts/ndarray/terms/max/max.md b/content/numpy/concepts/ndarray/terms/max/max.md new file mode 100644 index 00000000000..775d445ef7f --- /dev/null +++ b/content/numpy/concepts/ndarray/terms/max/max.md @@ -0,0 +1,110 @@ +--- +Title: 'max()' +Description: 'Returns the maximum value in a NumPy array, optionally along a specified axis.' +Subjects: + - 'Computer Science' + - 'Data Science' +Tags: + - 'Array' + - 'Data' + - 'NumPy' +CatalogContent: + - 'learn-python-3' + - 'paths/data-science' +--- + +The **`ndarray.max()`** method returns the largest element in a NumPy array. The operation can run on the entire flattened array or along a chosen axis, and supports optional parameters for masking, output arrays, and dimension preservation. + +## Syntax + +```pseudo +ndarray.max(axis=None, out=None, keepdims=False, initial=, where=True) +``` + +**Parameters:** + +- `axis` (optional): Axis along which the maximum is computed. + - `None`: searches the entire array + - `0`: column-wise + - `1`: row-wise +- `out` (optional): Output array that receives the result. +- `keepdims` (optional): Preserves reduced axes with length 1, keeping the array's dimensionality. +- `initial` (optional): A default value to compare against when the array is empty. +- `where` (optional): Boolean mask indicating which elements to include in the comparison. + +**Return value:** + +The maximum value as a scalar or array, depending on the axis and output parameters. + +## Example 1: Maximum Value in a 1D Array + +In this example, the array is scanned for its largest value, and the maximum element is returned: + +```py +import numpy as np + +arr = np.array([4, 12, 7, 19, 3]) +result = arr.max() +print(result) +``` + +The output of this code is: + +```shell +19 +``` + +## Example 2: Maximum Values Along Columns + +In this example, `max()` is applied along axis 0, producing one maximum value per column in the 2D array: + +```py +import numpy as np + +arr = np.array([[2, 8, 5], + [9, 3, 7]]) + +result = arr.max(axis=0) +print(result) +``` + +The output of this code is: + +```shell +[9 8 7] +``` + +## Codebyte Example + +In this example, the `max()` method is used to compute the global maximum, row-wise maximums, and a masked maximum using both where and initial to avoid reduction errors: + +```codebyte/python +import numpy as np + +arr = np.array([[10, 4, 6], + [3, 15, 2], + [8, 1, 9]]) + +global_max = arr.max() +row_max = arr.max(axis=1) + +masked_max = arr.max(where=arr > 5, initial=-np.inf) + +print("Maximum in entire array:", global_max) +print("Maximum in each row:", row_max) +print("Maximum among values greater than 5:", masked_max) +``` + +## Frequently Asked Questions + +### 1. What is Max NumPy in Python? + +In NumPy, `max()` is a method that returns the largest value within an array or along a chosen axis. The operation relies on efficient vectorized comparisons, making it significantly faster than manual iteration over Python lists. + +### 2. What is Max in NumPy select? + +In the context of `numpy.select`, `max()` often appears as a reduction step to extract the highest value from conditional outputs. Although `select()` focuses on choosing values based on conditions, `max()` can be applied afterward to determine the largest result from the selected set. + +### 3. Can you use `max()` on a list? + +Python’s built-in `max()` function works on lists and returns their largest element. This behavior is independent of NumPy; however, NumPy arrays also integrate their own optimized `ndarray.max()` method for numerical operations.