Move equality functions here from GLUtilities

Author: galenlynch

Project.toml

@@ -1,7 +1,7 @@
 name = "SignalIndices"
 uuid = "18f53e89-494d-4131-905c-653e8ada6cd8"
 authors = ["Galen Lynch <galen@galenlynch.com>"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 IterTools = "c8e1da08-722c-5040-9ed9-7db0dc04731e"

README.md

@@ -44,7 +44,7 @@ maxima_indices = local_extrema(signal, >)
 minima_indices = local_extrema(signal, <)
 
 # Fast histogram for regularly-spaced bins
-counts = glhist(values, bin_edges)
+counts = uniformhist(values, bin_edges)
 ```
 
 ### Array Utilities
@@ -59,6 +59,12 @@ idx = find_closest(array, target)
 non_colliding = filter_no_collisions(events_a, events_b, min_gap)
 duplicates = find_not_unique(array)
 
+# Equality and comparison
+allsame([1, 1, 1])            # true — all elements equal
+allsame(length, [1,2], [3,4]) # true — all have same length
+anyeq(3, [1, 2, 3])           # true — element found in collection
+absdiff(5, 3)                 # 2 — absolute difference (unsigned-safe)
+
 # Iterator utilities
 result = sum(skipnothing([1, nothing, 2, nothing, 3]))  # 6
 ```
@@ -119,7 +125,7 @@ Pkg.develop(path="/path/to/SignalIndices")
 - `indices_above_thresh(arr, threshold)` - Contiguous regions above threshold
 - `local_extrema(signal, comp)` - Find local maxima/minima
 - `find_local_extrema(signal, start; findmax, right_on_ties)` - Hill-climb to extremum
-- `glhist(values, bins)` / `glhist!(counts, values, bins)` - Fast histogram
+- `uniformhist(values, bins)` / `uniformhist!(counts, values, bins)` - Fast histogram
 - `filter_no_collisions(as, bs, radius)` - Remove elements too close to reference
 - `window_counts(times, duration)` - Count events in sliding window
 
@@ -138,6 +144,9 @@ Pkg.develop(path="/path/to/SignalIndices")
 - `trailing_zeros_idx(arr)` - Last non-zero index
 - `clipsize!(vec, n)` - Resize and shrink capacity
 - `rev_view(vec)` - Reversed view
+- `allsame(collection)` / `allsame(f, args...)` - Check all elements (or mapped values) are equal
+- `anyeq(element, collection)` - Check if element exists in collection
+- `absdiff(a, b)` - Absolute difference (safe for unsigned integers)
 - `skipoftype(T, itr)` / `skipnothing(itr)` - Skip elements by type
 
 ## Citing

src/SignalIndices.jl

@@ -74,7 +74,10 @@ export
     clipsize!,
     find_not_unique,
     skipoftype,
-    skipnothing
+    skipnothing,
+    allsame,
+    anyeq,
+    absdiff
 
 div_type(::Type{N}) where {N<:AbstractFloat} = N
 div_type(::Type{N}) where {N<:Integer} = Float64
@@ -1108,4 +1111,28 @@ function indices_above_thresh(arr, thr)
     return out
 end
 
+allsame(f::Function, first) = true
+
+function allsame(f::Function, first, second, others...)
+    f(first) == f(second) && allsame(f, second, others...)
+end
+
+allsame(first, args...) = allsame(identity, first, args...)
+
+function allsame(a::AbstractArray)
+    isempty(a) && return true
+    @inbounds first = a[1]
+    for e in a[2:end]
+        if !isequal(e, first)
+            return false
+        end
+    end
+    true
+end
+
+anyeq(el, iter) = any(a -> a == el, iter)
+
+@inline absdiff(a::Unsigned, b::Unsigned) = ifelse(a <= b, b - a, a - b)
+@inline absdiff(a::Signed, b::Signed) = abs(a - b)
+
 end