◆ read()Read the column with given name or index.
There are several ways to read a column, which can be specified either by its name or 0-based index. The simplest way is to read the whole column as a new Example usages: // Create a new Column
auto from_name = columns.read<float>("RA");
auto from_index = columns.read<float>(1);
// Concatenate two columns into an existing Column
long row_count = read_row_count();
std::vector<float> values(row_count * 2);
columns.read_to("RA", ra);
columns.read_to("DEC", dec);
long read_row_count() const Get the current number of rows.
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