How do I extract data from a Deephaven table?

How can I get data out of a Deephaven table and into Python objects?

Use the deephaven.numpy or deephaven.pandas module. to_numpy copies table data into a NumPy array, and to_pandas copies it into a pandas DataFrame. Both take an optional cols argument to copy only the columns you need.

from deephaven.numpy import to_numpy
from deephaven.pandas import to_pandas
from deephaven import empty_table

table = empty_table(10).update(["X = ii", "Y = sqrt(X)"])

x_np = to_numpy(table, cols=["X"]).flatten()
print(x_np)

x_pd = to_pandas(table, cols=["X"])
print(x_pd)

Note

Both functions copy the data into memory. For large tables, use table operations such as where or view first so that only the data you need is copied.

For other ways to get data out of a table, see:

Extract table values: read individual values, iterate over a column with a for loop, and access values by row key.
Table iterators: loop over rows as dictionaries or tuples, one row or one chunk at a time.
deephaven.learn: gather table data into Python objects for calculations and scatter the results back into new table columns.

Note

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