fix

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

src/abstractdataframe/abstractdataframe.jl

@@ -150,21 +150,21 @@ rename(f::Function, df::AbstractDataFrame)
 
 * `::AbstractDataFrame` : the updated result
 
-New names are processed sequentially. A new name must not already exist in the `DataFrame`
-at the moment an attempt to rename a column is performed.
+Each name is changed at most once. Permutation of names is allowed.
 
 **Examples**
 
 ```julia
 df = DataFrame(i = 1:10, x = rand(10), y = rand(["a", "b", "c"], 10))
 rename(df, :i => :A, :x => :X)
+rename(df, :x => :y, :y => :x)
 rename(df, [:i => :A, :x => :X])
 rename(df, Dict(:i => :A, :x => :X))
 rename(x -> Symbol(uppercase(string(x))), df)
 rename(df) do x
     Symbol(uppercase(string(x)))
 end
-rename!(df, Dict(:i =>: A, :x => :X))
+rename!(df, Dict(:i => :A, :x => :X))
 ```
 
 """

src/other/index.jl

@@ -46,14 +46,23 @@ function names!(x::Index, nms::Vector{Symbol}; makeunique::Bool=false)
 end
 
 function rename!(x::Index, nms)
-    n = length(nms)
-    nfrom = length(unique(getindex.(nms, 1)))
-    nto = length(unique(getindex.(nms, 2)))
-    n > nfrom && throw(ArgumentError("Tried renaming a column multiple times."))
-    n > nto && throw(ArgumentError("Tried renaming to a column multiple times."))
     xbackup = copy(x)
+    processedfrom = Set(Symbol[])
+    processedto = Set(Symbol[])
     toholder = Dict{Symbol,Int}()
     for (from, to) in nms
+        if from ∈ processedfrom
+            copy!(x.lookup, xbackup.lookup)
+            x.names .= xbackup.names
+            throw(ArgumentError("Tried renaming a name multiple times."))
+        end
+        if to ∈ processedto
+            copy!(x.lookup, xbackup.lookup)
+            x.names .= xbackup.names
+            throw(ArgumentError("Tried renaming to a name multiple times."))
+        end
+        push!(processedfrom, from)
+        push!(processedto, to)
         from == to && continue # No change, nothing to do
         if !haskey(xbackup, from)
             copy!(x.lookup, xbackup.lookup)

test/dataframe.jl

@@ -1146,12 +1146,12 @@ end
     @test names(df) == [:A, :B, :C]
     @test_throws ArgumentError rename!(df, :A => :B)
     @test names(df) == [:A, :B, :C]
-    @test_throws ArgumentError rename!(df, :A => :B, :B => :A, :C => :B)
-    @test names(df) == [:A, :B, :C]
-    @test_throws ArgumentError rename!(df, :A => :X, :A => :Y)
+    @test_throws ArgumentError rename!(df, :A => :X, :A => :X)
     @test names(df) == [:A, :B, :C]
     @test_throws ArgumentError rename!(df, :A => :X, :B => :X)
     @test names(df) == [:A, :B, :C]
+    @test_throws ArgumentError rename!(df, :A => :B, :B => :A, :C => :B)
+    @test names(df) == [:A, :B, :C]
     @test_throws ArgumentError rename!(df, :A => :B, :B => :A, :A => :X)
     @test names(df) == [:A, :B, :C]
 end