How can I convert an integer date to a formatted date string?

I have a column containing dates as integers (like 20250401). How can I convert these to formatted date strings (YYYY-MM-DD) in Deephaven?

The best practice is to first format the integer as a proper date string, then use the built-in parseLocalDate function:

from deephaven import new_table
from deephaven.column import int_col

# Sample table with integer dates
t = new_table([int_col("DateInt", [20230101, 20240215, 20250401, 20260630])])

# Best practice: Format as string, then parse as LocalDate
result = t.update(
    [
        "Year = (int)(DateInt / 10000)",
        "Month = (int)((DateInt % 10000) / 100)",
        "Day = (int)(DateInt % 100)",
        "DateString = String.format(`%04d-%02d-%02d`, Year, Month, Day)",
        "DateFormatted = parseLocalDate(DateString)",
    ]
)

This approach works by:

1. Extracting the year by dividing the integer by 10000 (e.g., 20250401 / 10000 = 2025).
2. Extracting the month by taking the remainder after dividing by 10000, then dividing by 100 (e.g., 20250401 % 10000 = 401, then 401 / 100 = 4).
3. Extracting the day by taking the remainder after dividing by 100 (e.g., 20250401 % 100 = 1).
4. Using java.lang.String.format to create a properly formatted ISO date string (YYYY-MM-DD).
5. Using parseLocalDate to convert the string to a proper LocalDate object.

This is the recommended approach because:

• It creates proper LocalDate objects that can be used for further date operations.
• It handles date validation automatically through parseLocalDate.
• It follows Deephaven best practices by using built-in parsing functions.
• The resulting LocalDate objects work seamlessly with other time-based functions.