add documentation for @pivot_longer with all columns

Author: cnrrobertson

docs/examples/UserGuide/pivots.jl

@@ -36,6 +36,18 @@ df_wide = DataFrame(id = [1, 2], A = [1, 3], B = [2, 4])
 
 @pivot_longer(df_wide, -id)
 
+# The selected columns can also be included as an array
+
+@pivot_longer(df_wide, [id, B])
+
+# or excluded
+
+@pivot_longer(df_wide, -[id, B])
+
+# If all columns should be included, they can be specified by either `everything()`, `:`, or by leaving the argument blank
+
+@pivot_longer(df_wide, everything())
+
 # In this example, we set the `names_to` and `values_to` arguments. Either argument can be left out and will revert to the default value. The `names_to` and `values_to` arguments can be provided as strings or as bare unquoted variable names.
 
 # Here is an example with `names_to` and `values_to` containing strings:
@@ -45,3 +57,4 @@ df_wide = DataFrame(id = [1, 2], A = [1, 3], B = [2, 4])
 # And here is an example with `names_to` and `values_to` containing bare unquoted variables:
 
 @pivot_longer(df_wide, A:B, names_to = letter, values_to = number)
+

test/test_pivots.jl

@@ -21,7 +21,7 @@ end
         )
     test_long1 = @pivot_longer(test_df, -label)
     test_long2 = @pivot_longer(test_df, name:num)
-    
+
     true_long3 = DataFrame(
         name = ["A","B","A","B"],
         num = [1,2,3,4],
@@ -37,21 +37,22 @@ end
         value = [1,1,2,2,1,2,3,4],
     )
     test_long5 = @pivot_longer(test_df, [label,num])
-    
+
     true_long6 = DataFrame(
         label = [1,1,2,2],
         num = [1,2,3,4],
         variable = ["name","name","name","name"],
         value = ["A","B","A","B"],
     )
     test_long6 = @pivot_longer(test_df, -[label,num])
-    
+
     true_long7 = DataFrame(
         variable = ["label","label","label","label","name","name","name","name","num","num","num","num"],
         value = [1,1,2,2,"A","B","A","B",1,2,3,4],
     )
     test_long7 = @pivot_longer(test_df, :)
     test_long8 = @pivot_longer(test_df)
+    test_long9 = @pivot_longer(test_df, everything())
 
     @test all(Array(true_long1 .== test_long1))
     @test all(Array(true_long1 .== test_long2))
@@ -61,5 +62,6 @@ end
     @test all(Array(true_long6 .== test_long6))
     @test all(Array(true_long7 .== test_long7))
     @test all(Array(true_long7 .== test_long8))
+    @test all(Array(true_long7 .== test_long9))
 end
 end