Add options for tolerance

Author: ajkeller34

src/indexing.jl

@@ -4,8 +4,10 @@ using Base: ViewIndex, @propagate_inbounds, tail
 
 immutable Value{T}
     val::T
+    tol::T
 end
-atvalue(x) = Value(x)
+Value(v,t) = Value(promote(v,t)...)
+atvalue(x; rtol=Base.rtoldefault(typeof(x)), atol=zero(x)) = Value(x, atol+rtol*abs(x))
 
 # Defer IndexStyle to the wrapped array
 @compat Base.IndexStyle{T,N,D,Ax}(::Type{AxisArray{T,N,D,Ax}}) = IndexStyle(D)
@@ -179,16 +181,23 @@ axisindexes(t, ax, idx) = error("cannot index $(typeof(ax)) with $(typeof(idx));
 # Maybe extend error message to all <: Numbers if Base allows it?
 axisindexes(::Type{Dimensional}, ax::AbstractVector, idx::Real) =
     throw(ArgumentError("invalid index: $idx. Use `atvalue` when indexing by value."))
-axisindexes(::Type{Dimensional}, ax::AbstractVector, idx) =
-    _axisindexes(Dimensional, ax::AbstractVector, idx)
-# Dimensional axes may always be indexed by value if in a Value type wrapper.
-axisindexes(::Type{Dimensional}, ax::AbstractVector, idx::Value) =
-    _axisindexes(Dimensional, ax::AbstractVector, idx.val)
-function _axisindexes(::Type{Dimensional}, ax::AbstractVector, idx)
+function axisindexes(::Type{Dimensional}, ax::AbstractVector, idx)
     idxs = searchsorted(ax, ClosedInterval(idx,idx))
     length(idxs) > 1 && error("more than one datapoint lies on axis value $idx; use an interval to return all values")
     idxs[1]
 end
+# Dimensional axes may always be indexed by value if in a Value type wrapper.
+function axisindexes(::Type{Dimensional}, ax::AbstractVector, idx::Value)
+    idxs = searchsorted(ax, ClosedInterval(idx.val,idx.val))
+    length(idxs) > 1 && error("more than one datapoint lies on axis value $idx; use an interval to return all values")
+    if length(idxs) == 1
+        idxs[1]
+    else # it's zero
+        last(idxs) > 0 && abs(ax[last(idxs)] - idx.val) < idx.tol && return last(idxs)
+        first(idxs) <= length(ax) && abs(ax[first(idxs)] - idx.val) < idx.tol && return first(idxs)
+        return 0
+    end
+end
 
 # Dimensional axes may be indexed by intervals to select a range
 axisindexes{T}(::Type{Dimensional}, ax::AbstractVector{T}, idx::ClosedInterval) = searchsorted(ax, idx)

test/indexing.jl

@@ -178,6 +178,9 @@ A = AxisArray([1 2; 3 4], Axis{:x}([1.0,4.0]), Axis{:y}([2.0,6.1]))
 @test @inferred(A[:, atvalue(2.0)]) == [1,3]
 @test @inferred(A[Axis{:x}(atvalue(4.0))]) == [3,4]
 @test @inferred(A[Axis{:y}(atvalue(6.1))]) == [2,4]
+@test @inferred(A[Axis{:x}(atvalue(4.00000001))]) == [3,4]
+@test @inferred(A[Axis{:x}(atvalue(2.0, atol=5))]) == [1,2]
+@test_throws BoundsError A[Axis{:x}(atvalue(4.00000001, rtol=0))]
 
 # Indexing by value directly is forbidden for indexes that are Real
 @test_throws ArgumentError A[4.0]