zero with element instead of eltype in pad (#176)

* zero with element instead of eltype in pad

* add tests

* call inplace variant in pad

* use loop instead of broadcast in inplace pad

* bugfix in test

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.6.16"
+version = "0.6.17"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/LinearAlgebra/helper.jl

@@ -216,31 +216,23 @@ function unsafe_resize!(W::AbstractMatrix,n::Integer,m::Integer)
 end
 
 
-function pad!(f::AbstractVector{T},n::Integer) where T
-	if n > length(f)
-		append!(f,zeros(T,n - length(f)))
-	else
-		resize!(f,n)
+function pad!(f::AbstractVector, n::Integer)
+    m = length(f)
+	resize!(f,n)
+	if n > m
+        z = m > 0 ? zero(f[1]) : zero(eltype(f))
+        for i in m+1:n
+            f[i] = z
+        end
 	end
+    f
 end
 
-
-function pad(f::AbstractVector{T},n::Integer) where T
-	if n > length(f)
-	   ret=Vector{T}(undef, n)
-	   ret[1:length(f)]=f
-	   for j=length(f)+1:n
-	       ret[j]=zero(T)
-	   end
-       ret
-	else
-        f[1:n]
-	end
-end
+pad(f::AbstractVector, n::Integer) = pad!(Vector(f), n)
 
 function pad(f::AbstractVector{Any},n::Integer)
 	if n > length(f)
-        Any[f...,zeros(n - length(f))...]
+        Any[f; zeros(n - length(f))]
 	else
         f[1:n]
 	end

test/runtests.jl

@@ -1,5 +1,6 @@
 using ApproxFunBase, LinearAlgebra, Random, Test
 import ApproxFunBase: ∞
+using ApproxFunOrthogonalPolynomials
 
 @testset "Helper" begin
     @testset "interlace" begin
@@ -42,6 +43,27 @@ import ApproxFunBase: ∞
         # check that unknown types don't lead to a stack overflow
         @test_throws MethodError ApproxFunBase.dot(DotTester())
     end
+    @testset "pad" begin
+        @testset "float" begin
+            @testset for T in [Float64, Any]
+                a = T[1,2,3]
+                b = @inferred pad(a, 4)
+                @test length(b) == 4
+                @test @view(b[1:3]) == a
+                @test b[end] == 0
+                @test pad(a, 2) == @view(a[1:2])
+            end
+        end
+        @testset "Fun" begin
+            f = Fun()
+            zf = zero(f)
+            @test (@inferred pad([f], 3)) == [f, zf, zf]
+            @test (@inferred pad([f, zf], 1)) == [f]
+            v = [f, zf]
+            @test @inferred pad!(v, 1) == [f]
+            @test length(v) == 1
+        end
+    end
 
     # TODO: Tensorizer tests
 end