From 1d4e0d028638ceebcb0ba407f819ec2f99dde73a Mon Sep 17 00:00:00 2001
From: Kristoffer Carlsson <kristoffer.carlsson@chalmers.se>
Date: Wed, 13 Jul 2016 13:38:45 -0700
Subject: [PATCH] Revise setindex!(A::SparseMatrixCSC, x, I::AbstractVector)
 such that it no longer expunges stored entries on zero assignment. Also add
 tests.

---
 base/sparse/sparsematrix.jl | 21 +++++++++------------
 test/sparsedir/sparse.jl    | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/base/sparse/sparsematrix.jl b/base/sparse/sparsematrix.jl
index 949d54b7e76f8d..087e1c6714b24b 100644
--- a/base/sparse/sparsematrix.jl
+++ b/base/sparse/sparsematrix.jl
@@ -2937,7 +2937,7 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
 
     colptrA = A.colptr; rowvalA = A.rowval; nzvalA = A.nzval; szA = size(A)
     colptrB = colptrA; rowvalB = rowvalA; nzvalB = nzvalA
-    nadd = ndel = 0
+    nadd = 0
     bidx = aidx = 1
 
     S = issorted(I) ? (1:n) : sortperm(I)
@@ -2963,8 +2963,8 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
             r2 = Int(colptrA[col+1] - 1)
 
             # copy from last position till current column
-            if (nadd > 0) || (ndel > 0)
-                colptrB[(lastcol+1):col] = colptrA[(lastcol+1):col] .+ (nadd - ndel)
+            if (nadd > 0)
+                colptrB[(lastcol+1):col] = colptrA[(lastcol+1):col] .+ nadd
                 copylen = r1 - aidx
                 if copylen > 0
                     copy!(rowvalB, bidx, rowvalA, aidx, copylen)
@@ -2981,7 +2981,7 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
         if r1 <= r2
             copylen = searchsortedfirst(rowvalA, row, r1, r2, Forward) - r1
             if (copylen > 0)
-                if (nadd > 0) || (ndel > 0)
+                if (nadd > 0)
                     copy!(rowvalB, bidx, rowvalA, r1, copylen)
                     copy!(nzvalB, bidx, nzvalA, r1, copylen)
                 end
@@ -2992,12 +2992,13 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
         end
 
         # 0: no change, 1: update, 2: delete, 3: add new
-        mode = ((r1 <= r2) && (rowvalA[r1] == row)) ? ((v == 0) ? 2 : 1) : ((v == 0) ? 0 : 3)
+        mode = ((r1 <= r2) && (rowvalA[r1] == row)) ? 1 : ((v == 0) ? 0 : 3)
 
-        if (mode > 1) && (nadd == 0) && (ndel == 0)
+        if (mode > 1) && (nadd == 0)
             # copy storage to take changes
             colptrA = copy(colptrB)
             memreq = (x == 0) ? 0 : n
+            # see comment/TODO for same statement in preceding logical setindex! method
             rowvalA = copy(rowvalB)
             nzvalA = copy(nzvalB)
             resize!(rowvalB, length(rowvalA)+memreq)
@@ -3009,10 +3010,6 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
             bidx += 1
             aidx += 1
             r1 += 1
-        elseif mode == 2
-            r1 += 1
-            aidx += 1
-            ndel += 1
         elseif mode == 3
             rowvalB[bidx] = row
             nzvalB[bidx] = v
@@ -3022,8 +3019,8 @@ function setindex!{Tv,Ti,T<:Real}(A::SparseMatrixCSC{Tv,Ti}, x, I::AbstractVecto
     end
 
     # copy the rest
-    @inbounds if (nadd > 0) || (ndel > 0)
-        colptrB[(lastcol+1):end] = colptrA[(lastcol+1):end] .+ (nadd - ndel)
+    @inbounds if (nadd > 0)
+        colptrB[(lastcol+1):end] = colptrA[(lastcol+1):end] .+ nadd
         r1 = colptrA[end]-1
         copylen = r1 - aidx + 1
         if copylen > 0
diff --git a/test/sparsedir/sparse.jl b/test/sparsedir/sparse.jl
index 33a00dbb1c10ae..47e94324ba2dac 100644
--- a/test/sparsedir/sparse.jl
+++ b/test/sparsedir/sparse.jl
@@ -699,6 +699,20 @@ let A = speye(Int, 5), I=1:10, X=reshape([trues(10); falses(15)],5,5)
     @test A[I] == A[X] == [1,0,0,0,0,0,1,0,0,0]
     A[I] = [1:10;]
     @test A[I] == A[X] == collect(1:10)
+    A[I] = zeros(Int, 10)
+    @test nnz(A) == 13
+    @test countnz(A) == 3
+    @test A[I] == A[X] == zeros(Int, 10)
+    c = collect(11:20); c[1] = c[3] = 0
+    A[I] = c
+    @test nnz(A) == 13
+    @test countnz(A) == 11
+    @test A[I] == A[X] == c
+    A = speye(Int, 5)
+    A[I] = c
+    @test nnz(A) == 12
+    @test countnz(A) == 11
+    @test A[I] == A[X] == c
 end
 
 let S = sprand(50, 30, 0.5, x->round(Int,rand(x)*100)), I = sprand(Bool, 50, 30, 0.2)