pathwaycom/pathway · error · ValueError

Table.interpolate(): Invalid column reference for the parame

Error message

Table.interpolate(): Invalid column reference for the parameter value, found a string. Did you mean this.{value} instead of {repr(value)}?

What it means

Error "Table.interpolate(): Invalid column reference for the parameter value, found a string. Did you mean this.{value} instead of {repr(value)}?" thrown in pathwaycom/pathway.

Source

Thrown at python/pathway/stdlib/statistical/_interpolate.py:130

        if isinstance(timestamp, str):
            raise ValueError(
                "Table.interpolate(): Invalid column reference for the parameter timestamp,"
                + f" found a string. Did you mean this.{timestamp} instead of {repr(timestamp)}?"
            )
        raise ValueError(
            "Table.interpolate(): Invalid column reference for the parameter timestamp."
        )

    ordered_table = self.sort(key=timestamp)

    table = self

    for value in values:
        if isinstance(value, pw.ColumnReference):
            value = self[value]
        else:
            if isinstance(value, str):
                raise ValueError(
                    "Table.interpolate(): Invalid column reference for the parameter value,"
                    + f" found a string. Did you mean this.{value} instead of {repr(value)}?"
                )
            raise ValueError(
                "Table.interpolate(): Invalid column reference for the parameter value."
            )
        assert timestamp.name != value.name

        sorted_timestamp_value = ordered_table + self.select(
            timestamp=timestamp, value=value
        )

        table_with_prev_next = _retrieve_prev_next_values(sorted_timestamp_value)

        interpolated_table = table_with_prev_next + sorted_timestamp_value

        prev_tab = interpolated_table.ix(pw.this.prev_value, optional=True)
        next_tab = interpolated_table.ix(pw.this.next_value, optional=True)

View on GitHub (pinned to fa2f74a464)

Solutions

1. Pass a ColumnReference for the value parameter, e.g. this.value instead of the string 'value'.

Example fix

t.interpolate(this.timestamp, this.value)

When it happens

Trigger: Thrown at python/pathway/stdlib/statistical/_interpolate.py:130 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/4d10b3cd04b1867c. Report an issue: GitHub.