diff --git a/pkg/resampler/resampler.go b/pkg/resampler/resampler.go index 26cead0..ebc7e88 100644 --- a/pkg/resampler/resampler.go +++ b/pkg/resampler/resampler.go @@ -8,20 +8,20 @@ import ( "github.com/ClusterCockpit/cc-backend/pkg/schema" ) -func SimpleResampler(data []schema.Float, old_frequency int64, new_frequency int64) ([]schema.Float, error) { - if old_frequency == 0 || new_frequency == 0 { - return nil, errors.New("either old or new frequency is set to 0") +func SimpleResampler(data []schema.Float, old_frequency int64, new_frequency int64) ([]schema.Float, int64, error) { + if old_frequency == 0 || new_frequency == 0 || new_frequency <= old_frequency { + return data, old_frequency, nil } if new_frequency%old_frequency != 0 { - return nil, errors.New("new sampling frequency should be multiple of the old frequency") + return nil, 0, errors.New("new sampling frequency should be multiple of the old frequency") } var step int = int(new_frequency / old_frequency) var new_data_length = len(data) / step if new_data_length == 0 || len(data) < 100 || new_data_length >= len(data) { - return data, nil + return data, old_frequency, nil } new_data := make([]schema.Float, new_data_length) @@ -30,14 +30,14 @@ func SimpleResampler(data []schema.Float, old_frequency int64, new_frequency int new_data[i] = data[i*step] } - return new_data, nil + return new_data, new_frequency, nil } // Inspired by one of the algorithms from https://skemman.is/bitstream/1946/15343/3/SS_MSthesis.pdf // Adapted from https://github.com/haoel/downsampling/blob/master/core/lttb.go func LargestTriangleThreeBucket(data []schema.Float, old_frequency int, new_frequency int) ([]schema.Float, int, error) { - if old_frequency == 0 || new_frequency == 0 { + if old_frequency == 0 || new_frequency == 0 || new_frequency <= old_frequency { return data, old_frequency, nil }