upper bound on majority classes in 'auto' balancing strategy

src/LarvaDatasets.jl

@@ -209,7 +209,7 @@ function labelcounts(files, timebefore::AbstractFloat, timeafter::AbstractFloat;
 end
 
 """
-    balancedcounts(observed_counts, target_count=nothing, majority_weight=2)
+    balancedcounts(observed_counts, targetcount=nothing, majorityweight=2)
 
 Derive sample sizes for all labels.
 
@@ -221,6 +221,8 @@ labels.
 
 If `target_count` is set, sample sizes are adjusted so that the total sample size equals this
 value. If too few occurences of a label are found, an error is thrown.
+
+See also [`thresholdedcounts`](@ref).
 """
 function balancedcounts(counts, targetcount=nothing, majorityweight=2)
     counts = typeof(counts)(k=>count for (k, count) in pairs(counts) if 0 < count)
@@ -248,6 +250,19 @@ function balancedcounts(counts, targetcount=nothing, majorityweight=2)
     return Dict{eltype(keys(counts)), Int}(zip(keys(counts), balancedcounts)), sum(balancedcounts)
 end
 
+"""
+    thresholdedcounts(observed_counts, majorityweight=10)
+
+Derive sample sizes for all labels, with an upper bound set as `majorityweight` times
+the cardinal of the least represented class.
+"""
+function thresholdedcounts(counts; majorityweight=10)
+    counts = typeof(counts)(k=>count for (k, count) in pairs(counts) if 0 < count)
+    majoritythresh = minimum(values(counts)) * majorityweight
+    thresholdedcounts = Dict(k=>(count < majoritythresh ? count : majoritythresh) for (k, count) in pairs(counts))
+    return thresholdedcounts, sum(values(thresholdedcounts))
+end
+
 function write_larva_dataset_hdf5(path, counts, files, refs, nsteps_before, nsteps_after;
         fixmwt=false, frameinterval=nothing,
     )
@@ -478,7 +493,7 @@ function write_larva_dataset_hdf5(output_dir::String,
         repository = input_data
         labelledfiles(repository, chunks; selection_rule=file_filter, shallow=shallow)
     elseif eltype(input_data) === String
-        [preload(f) for f in input_data]
+        preload.(input_data)
     else
         input_data
     end
@@ -507,9 +522,8 @@ function write_larva_dataset_hdf5(output_dir::String,
     if balance
         sample_sizes, total_sample_size = balancedcounts(counts, sample_size)
     else
-        sample_sizes = counts
-        total_sample_size = sum(values(sample_sizes))
         isnothing(sample_size) || @error "Argument sample_size not supported for the specified balancing strategy"
+        sample_sizes, total_sample_size = thresholdedcounts(counts)
     end
     @info "Sample sizes (observed, selected):" [Symbol(label) => (count, get(sample_sizes, label, 0)) for (label, count) in pairs(counts)]...
     date = Dates.format(Dates.now(), "yyyy_mm_dd")