change order of arguments in fkeep, fix bug with fixed elements

src/sparsematrix.jl

@@ -1653,7 +1653,7 @@ end
 ## fkeep! and children tril!, triu!, droptol!, dropzeros[!]
 
 """
-    fkeep!(A::AbstractSparseArray, f)
+    fkeep!(f, A::AbstractSparseArray)
 
 Keep elements of `A` for which test `f` returns `true`. `f`'s signature should be
 
@@ -1673,15 +1673,15 @@ julia> A = sparse(Diagonal([1, 2, 3, 4]))
  ⋅  ⋅  3  ⋅
  ⋅  ⋅  ⋅  4
 
-julia> SparseArrays.fkeep!(A, (i, j, v) -> isodd(v))
+julia> SparseArrays.fkeep!((i, j, v) -> isodd(v), A)
 4×4 SparseMatrixCSC{Int64, Int64} with 2 stored entries:
  1  ⋅  ⋅  ⋅
  ⋅  ⋅  ⋅  ⋅
  ⋅  ⋅  3  ⋅
  ⋅  ⋅  ⋅  ⋅
 ```
 """
-function _fkeep!(A::AbstractSparseMatrixCSC, f::F) where F
+function _fkeep!(f::F, A::AbstractSparseMatrixCSC) where F<:Function
     An = size(A, 2)
     Acolptr = getcolptr(A)
     Arowval = rowvals(A)
@@ -1716,34 +1716,39 @@ function _fkeep!(A::AbstractSparseMatrixCSC, f::F) where F
     return A
 end
 
-function _fkeep!_fixed(A::AbstractSparseMatrixCSC, f::F) where F
+function _fkeep!_fixed(f::F, A::AbstractSparseMatrixCSC) where F<:Function
     @inbounds for j in axes(A, 2)
         for k in getcolptr(A)[j]:getcolptr(A)[j+1]-1
-            i = rowvals(A)[k]
-            x = nonzeros(A)[k]
             # If this element should be kept, rewrite in new position
-            if f(Ai, Aj, Ax)
+            if !f(rowvals(A)[k], j, nonzeros(A)[k])
                 nonzeros(A)[k] = zero(eltype(A))
             end
         end
     end
     return A
 end
 
-fkeep!(A::AbstractSparseMatrixCSC, f::F) where F= _is_fixed(A) ? _fkeep!_fixed(A, f) : _fkeep!(A, f)
+fkeep!(f::F, A::AbstractSparseMatrixCSC) where F<:Function = _is_fixed(A) ? _fkeep!_fixed(f, A) : _fkeep!(f, A)
+
+# deprecated syntax
+function fkeep!(x::Union{AbstractSparseMatrixCSC,AbstractCompressedVector},f::F) where F<:Function
+    Base.depwarn("`fkeep!(x, f::Function)` is deprecated, use `fkeep!(f::Function, x)` instead.", :fkeep!)
+    return fkeep!(f, x)
+end
+
 
 tril!(A::AbstractSparseMatrixCSC, k::Integer = 0) =
-    fkeep!(A, (i, j, x) -> i + k >= j)
+    fkeep!((i, j, x) -> i + k >= j, A)
 triu!(A::AbstractSparseMatrixCSC, k::Integer = 0) =
-    fkeep!(A, (i, j, x) -> j >= i + k)
+    fkeep!((i, j, x) -> j >= i + k, A)
 
 """
     droptol!(A::AbstractSparseMatrixCSC, tol)
 
 Removes stored values from `A` whose absolute value is less than or equal to `tol`.
 """
 droptol!(A::AbstractSparseMatrixCSC, tol) =
-    fkeep!(A, (i, j, x) -> abs(x) > tol)
+    fkeep!((i, j, x) -> abs(x) > tol, A)
 
 """
     dropzeros!(A::AbstractSparseMatrixCSC;)
@@ -1754,7 +1759,7 @@ For an out-of-place version, see [`dropzeros`](@ref). For
 algorithmic information, see `fkeep!`.
 """
 
-dropzeros!(A::AbstractSparseMatrixCSC) = _is_fixed(A) ? A : fkeep!(A, (i, j, x) -> _isnotzero(x))
+dropzeros!(A::AbstractSparseMatrixCSC) = _is_fixed(A) ? A : fkeep!((i, j, x) -> _isnotzero(x), A)
 
 """
     dropzeros(A::AbstractSparseMatrixCSC;)

src/sparsevector.jl

@@ -2074,31 +2074,36 @@ function sort(x::AbstractCompressedVector{Tv,Ti}; kws...) where {Tv,Ti}
     typeof(x)(n,newnzind,newnzvals)
 end
 
-function fkeep!(x::AbstractCompressedVector, f)
-    _is_fixed(x) && return x
-
-    nzind = nonzeroinds(x)
-    nzval = nonzeros(x)
-
-    x_writepos = 1
-    @inbounds for xk in 1:nnz(x)
-        xi = nzind[xk]
-        xv = nzval[xk]
-        # If this element should be kept, rewrite in new position
-        if f(xi, xv)
-            if x_writepos != xk
-                nzind[x_writepos] = xi
-                nzval[x_writepos] = xv
+function fkeep!(f, x::AbstractCompressedVector{Tv}) where Tv
+    if _is_fixed(x)
+        for i in 1:nnz(x)
+            if !f(nonzeroinds(x)[i], nonzeros(x)[i])
+                nonzeros(x)[i] = zero(Tv)
+            end
+        end
+    else
+        nzind = nonzeroinds(x)
+        nzval = nonzeros(x)
+
+        x_writepos = 1
+        @inbounds for xk in 1:nnz(x)
+            xi = nzind[xk]
+            xv = nzval[xk]
+            # If this element should be kept, rewrite in new position
+            if f(xi, xv)
+                if x_writepos != xk
+                    nzind[x_writepos] = xi
+                    nzval[x_writepos] = xv
+                end
+                x_writepos += 1
             end
-            x_writepos += 1
         end
-    end
-
-    # Trim x's storage if necessary
-    x_nnz = x_writepos - 1
-    resize!(nzval, x_nnz)
-    resize!(nzind, x_nnz)
 
+        # Trim x's storage if necessary
+        x_nnz = x_writepos - 1
+        resize!(nzval, x_nnz)
+        resize!(nzind, x_nnz)
+    end
     return x
 end
 
@@ -2109,7 +2114,7 @@ end
 
 Removes stored values from `x` whose absolute value is less than or equal to `tol`.
 """
-droptol!(x::AbstractCompressedVector, tol) = fkeep!(x, (i, x) -> abs(x) > tol)
+droptol!(x::AbstractCompressedVector, tol) = fkeep!((i, x) -> abs(x) > tol, x)
 
 """
     dropzeros!(x::AbstractCompressedVector)
@@ -2119,7 +2124,7 @@ Removes stored numerical zeros from `x`.
 For an out-of-place version, see [`dropzeros`](@ref). For
 algorithmic information, see `fkeep!`.
 """
-dropzeros!(x::AbstractCompressedVector) = _is_fixed(x) ? x : fkeep!(x, (i, x) -> _isnotzero(x))
+dropzeros!(x::AbstractCompressedVector) = _is_fixed(x) ? x : fkeep!((i, x) -> _isnotzero(x), x)
 
 
 """

test/fixed.jl

@@ -1,6 +1,6 @@
 using Test, SparseArrays, LinearAlgebra
 using SparseArrays: AbstractSparseVector, AbstractSparseMatrixCSC, FixedSparseCSC, FixedSparseVector, ReadOnly,
-    getcolptr, rowvals, nonzeros, nonzeroinds, _is_fixed, fixed, move_fixed
+    getcolptr, rowvals, nonzeros, nonzeroinds, _is_fixed, fixed, move_fixed, fkeep!
 
 @testset "ReadOnly" begin
     v = randn(100)
@@ -124,3 +124,14 @@ end
     @test b == a
 end
 
+always_false(x...) = false
+@testset "Test fkeep!" begin
+    for a in [sprandn(10, 10, 0.99) + I, sprandn(10, 0.1) .+ 1]
+        a = fixed(a)
+        b = copy(a)
+        fkeep!(always_false, b)
+        @test nnz(a) == nnz(b)
+        @test all(iszero, nonzeros(b))
+
+    end
+end

test/sparsevector.jl

@@ -913,7 +913,7 @@ end
         @test_throws ArgumentError findmin(x)
         @test_throws ArgumentError findmax(x)
     end
-    
+
     let v = spzeros(3) #Julia #44978
         v[1] = 2
         @test argmin(v) == 2
@@ -1298,8 +1298,9 @@ end
     xdrop = copy(x)
     # This will keep index 1, 3, 4, 7 in xdrop
     f_drop(i, x) = (abs(x) == 1.) || (i in [1, 7])
-    SparseArrays.fkeep!(xdrop, f_drop)
+    SparseArrays.fkeep!(f_drop, xdrop)
     @test exact_equal(xdrop, SparseVector(7, [1, 3, 4, 7], [3., -1., 1., 3.]))
+    @test_deprecated SparseArrays.fkeep!(xdrop, f_drop)
 end
 
 @testset "dropzeros[!] with length=$m" for m in (10, 20, 30)