Source code for dpest.utils.nrelpar

def nrelpar(pst_path, new_value):
    """
    Updates the NRELPAR parameter in a PEST control (.pst) file.

    NRELPAR specifies the number of successive iterations over which the RELPARSTP
    criterion must be met for optimization termination. This function allows you
    to set NRELPAR to any integer value greater than zero.

    **Required Arguments:**
    =======
        * **pst_path** (*str*):
            Path to the .pst file to modify
        * **new_value** (*int*):
            New value for NRELPAR (must be an integer > 0)

    **Returns:**
    =======
        * ``None``

    **Example:**
    =======

    **Set NRELPAR to 3:**

        .. code-block:: python

            from dpest.utils import nrelpar

            nrelpar("PEST_CONTROL.pst", 3)
    """
    try:
        # Validate input
        if not isinstance(new_value, int):
            raise ValueError("NRELPAR must be an integer")
        if new_value <= 0:
            raise ValueError("NRELPAR must be greater than zero")

        with open(pst_path, 'r') as f:
            lines = f.readlines()

        # NRELPAR is the 6th value on line 9 (index 8)
        target_line_idx = 8
        if target_line_idx >= len(lines):
            raise IndexError(f"File has only {len(lines)} lines. Expected control data at line {target_line_idx + 1}.")

        current_line = lines[target_line_idx]
        values = current_line.split()

        if len(values) < 6:
            raise ValueError("NRELPAR position not found in control data line")

        # Replace sixth value (NRELPAR at index 5)
        values[5] = f"{new_value}"

        # Rebuild line with original formatting
        current_padding = len(current_line) - len(current_line.lstrip())
        new_line = " " * current_padding + "   ".join(values) + "\n"

        lines[target_line_idx] = new_line

        with open(pst_path, 'w') as f:
            f.writelines(lines)

    except FileNotFoundError:
        print(f"Error: File '{pst_path}' not found.")
    except ValueError as ve:
        print(f"ValueError: {str(ve)}")
    except IndexError as ie:
        print(f"IndexError: {str(ie)}")
    except Exception as e:
        print(f"Unexpected error: {str(e)}")