Allow permutaion of names in rename!

Signed-off-by: lizz <lizz@sensetime.com>

src/other/index.jl

@@ -46,14 +46,26 @@ function names!(x::Index, nms::Vector{Symbol}; makeunique::Bool=false)
 end
 
 function rename!(x::Index, nms)
+    xbackup = copy(x)
+    toholder = Dict()
     for (from, to) in nms
         from == to && continue # No change, nothing to do
-        if haskey(x, to)
+        if haskey(toholder, to)
+            copy!(x.lookup, xbackup.lookup)
+            x.names .= xbackup.names
             error("Tried renaming $from to $to, when $to already exists in the Index.")
         end
-        x.lookup[to] = col = pop!(x.lookup, from)
+        if haskey(x, to)
+            toholder[to] = x.lookup[to]
+        end
+        x.lookup[to] = col = haskey(toholder, from) ? pop!(toholder, from) : pop!(x.lookup, from)
         x.names[col] = to
     end
+    if !isempty(toholder)
+        copy!(x.lookup, xbackup.lookup)
+        x.names .= xbackup.names
+        error("Tried renaming to $(join(keys(toholder), ", ")), when it already exists in the Index.")
+    end
     return x
 end
 

test/dataframe.jl

@@ -1127,6 +1127,16 @@ end
     @test names(df) == [:A_4, :B_4]
     @test rename!(x->Symbol(lowercase(string(x))), df) === df
     @test names(df) == [:a_4, :b_4]
+
+    df = DataFrame(A = 1:3, B = 'A':'C', C = [:x, :y, :z])
+    @test rename!(df, :A => :B, :B => :A) === df
+    @test names(df) == [:B, :A, :C]
+    @test rename!(df, :A => :B, :B => :A, :C => :D) === df
+    @test names(df) == [:A, :B, :D]
+    @test rename!(df, :A => :B, :B => :C, :D => :A) === df
+    @test names(df) == [:B, :C, :A]
+    @test rename!(df, :A => :B, :B => :C, :C => :A) === df
+    @test names(df) == [:C, :A, :B]
 end
 
 @testset "size" begin