Alignment of complex numbers

src/abstractdataframe/show.jl

@@ -190,14 +190,25 @@ function _show(io::IO,
     # floating points.
     alignment_anchor_regex = Dict{Int, Vector{Regex}}()
 
-    # Columns composed of numbers are printed aligned to the right.
-    alignment_regex_vec = [r"\."]
+    # Regex to align real numbers.
+    alignment_regex_real = [r"\."]
+
+    # Regex for columns with complex numbers.
+    #
+    # Here we are matching `+` or `-` unless it is not at the beginning of the
+    # string or an `e` precedes it.
+    alignment_regex_complex = [r"(?<!^)(?<!e)[+-]"]
 
     for i = 1:num_cols
         type_i = nonmissingtype(types[i])
 
-        if type_i <: Number
-            alignment_anchor_regex[i] = alignment_regex_vec
+        if type_i <: Complex
+            alignment_anchor_regex[i] = alignment_regex_complex
+            alignment[i] = :r
+        elseif type_i <: Real
+            alignment_anchor_regex[i] = alignment_regex_real
+            alignment[i] = :r
+        elseif type_i <: Number
             alignment[i] = :r
         end
     end

test/show.jl

@@ -687,6 +687,52 @@ end
 
 end
 
+@testset "Complex number alignment" begin
+    a = Union{Missing, Number}[
+        im,
+        1 + im,
+        -1 - im,
+        1.123 + 123im,
+        -2.323 - 32im,
+        -1//3 - 4//5im,
+        1028.23123,
+        missing,
+        -0.304105,
+        2123123,
+        +0.304105,
+        1.3123e-10 + 1.123e-5im
+    ]
+    b = Int64[i ≤ 6 ? -1 * 10^(i - 1) : 10^(i - 7) for i = 1:12]
+    c = Union{Missing, Float64}[i == 5 ? missing : 10.0^(i-4) for i = 1:12]
+    d = ComplexF64[(-1)^(i % 3 == 0) * 10.0^(i-6) + (-1)^i * (10.0)^(11-i-6) * im for i = 1:12]
+    df = DataFrame(very_big_column_name_1 = a,
+                   very_big_column_name_2 = b,
+                   very_big_column_name_3 = c,
+                   very_big_column_name_4 = d)
+
+    io = IOContext(IOBuffer())
+    show(io, df)
+    str = String(take!(io.io))
+
+    @test str == """
+        12×4 DataFrame
+         Row │ very_big_column_name_1  very_big_column_name_2  very_big_column_name_3  very_big_column_name_4
+             │ Union{Missing, Number}  Int64                   Float64?                $(Complex{Float64})
+        ─────┼────────────────────────────────────────────────────────────────────────────────────────────────
+           1 │                     im                      -1                   0.001        1.0e-5-10000.0im
+           2 │                  1+1im                     -10                   0.01         0.0001+1000.0im
+           3 │                 -1-1im                    -100                   0.1          -0.001-100.0im
+           4 │          1.123+123.0im                   -1000                   1.0            0.01+10.0im
+           5 │          -2.323-32.0im                  -10000             missing               0.1-1.0im
+           6 │          -1//3+4//5*im                 -100000                 100.0            -1.0+0.1im
+           7 │                1028.23                       1                1000.0            10.0-0.01im
+           8 │                missing                      10               10000.0           100.0+0.001im
+           9 │              -0.304105                     100              100000.0         -1000.0-0.0001im
+          10 │                2123123                    1000                   1.0e6       10000.0+1.0e-5im
+          11 │               0.304105                   10000                   1.0e7      100000.0-1.0e-6im
+          12 │  1.3123e-10+1.123e-5im                  100000                   1.0e8        -1.0e6+1.0e-7im"""
+end
+
 @testset "Issue #2673 - Vertical line when not showing row numbers" begin
     df = DataFrame(a = Int64[10, 20], b = Int64[30, 40], c = Int64[50, 60])