rowfilter

Create a row filter expression.

📝Syntax

rf = rowfilter(names)
rf = rowfilter(T)
rf = rowfilter(info)

📥Input Arguments

Parameter	Description
names	variable names specified as a string array or cell array of character vectors.
T	a table or timetable whose variable names are used by the filter.
info	a nelson.io.parquet.ParquetInfo object whose variable names are used by the filter.

📤Output Arguments

Parameter	Description
rf	a nelson.io.RowFilter object.

📄Description

rowfilter creates a filter object that exposes variable names through dot notation.

Use relational operators >, >=, <, <=, ==, and ~= to create comparisons. Use logical operators &, |, and ~ to combine expressions.

The resulting object can be passed to parquetread or parquetDatastore with the RowFilter name-value pair. It can also be applied directly to a table with rf.apply(T).

💡Examples

T = table([1; 2; 3; 4], [10; 20; 30; 40], ...
  'VariableNames', {'Id', 'Value'});
rf = rowfilter(T);
R = (rf.Id >= 2 & rf.Value < 40).apply(T)

filename = [tempdir(), 'doc_rowfilter.parquet'];
T = table([1; 2; 3; 4], [10; 20; 30; 40], 'VariableNames', {'Id', 'Value'});
parquetwrite(filename, T);
info = parquetinfo(filename);
rf = rowfilter(info);
R = parquetread(filename, 'RowFilter', rf.Value >= 30)

🕔Version History

Version	Description
2.0.0	initial version

Edit this page on GitHub