update_view method creates a new table containing a new formula column for each argument.
update_view, the new columns are not stored in memory. Rather, a formula is stored that is used to recalculate each cell every time it is accessed.
The syntax for the
lazy_update methods is identical, as is the resulting table.
update_view is recommended when:
- the formula is fast to compute,
- only a small portion of the data is being accessed,
- cells are accessed very few times, or
- memory usage must be minimized.
For other cases, consider using
lazy_update. These methods have different memory and computation expenses.
update_view(formulas: Union[str, Sequence[str]]) -> Table
Formulas to compute columns in the new table; e.g.,
A new table that includes all the original columns from the source table and the newly defined formula columns.
In the following example, a new table containing the columns from the source table plus two new columns,
Y, is created.
from deephaven import new_table
from deephaven.column import string_col, int_col
source = new_table([
string_col("A", ["The", "At", "Is", "On"]),
int_col("B", [1, 2, 3, 4]),
int_col("C", [5, 6, 7, 8])
result = source.update_view(formulas=["X = B", "Y = sqrt(C)"])