Add analysis module with ZAA function

src/Analysis/Analysis.jl

+module Analysis
+
+using CryoGrid.Utils
+
+using DimensionalData
+using TimeSeries
+
+_check_array_dims(arr::AbstractDimArray) = @assert hasdim(arr, Z) && hasdim(arr, Ti) "array must have depth (Z) and time (Ti) dimensions"
+
+"""
+    zero_annual_amplitude(arr::AbstractDimArray{<:TempQuantity}; threshold=0.5u"°C")
+
+Computes annual depth of zero amplitude (where `|max - min| < threshold`) and returns the
+result for each year. Assumes `arr` to have dimensions `Ti` (time) and `Z` (depth) in any order.
+"""
+function zero_annual_amplitude(arr::AbstractDimArray{<:TempQuantity}; threshold=0.5u"°C")
+    _check_array_dims(arr)
+    tarr = TimeArray(dims(arr, Ti).val, permutedims(arr, (Ti,Z)))
+    annual_min = collapse(tarr, year, last, minimum)
+    annual_max = collapse(tarr, year, last, maximum)
+    z_inds = argmax(abs.(values(annual_min) .- values(annual_max)) .< threshold, dims=2)
+    rebuild(arr, dims(x, Z)[[i[2] for i in z_inds]], (Ti(timestamp(annual_max)),))
+end
+
+end
\ No newline at end of file