Add isapprox support for dataframes.

NEWS.md

@@ -38,7 +38,8 @@
 * add `rownumber` to `DataFrameRow` ([#2356](https://github.com/JuliaData/DataFrames.jl/pull/2356))
 * allow passing column name to specify the position where a new columns should be
   inserted in `insertcols!` ([#2365](https://github.com/JuliaData/DataFrames.jl/pull/2365))
-
+* add `isapprox` method to check for approximate equality between two dataframes
+  ([#2373](https://github.com/JuliaData/DataFrames.jl/pull/2373))
 ## Deprecated
 
 * `DataFrame!` is now deprecated ([#2338](https://github.com/JuliaData/DataFrames.jl/pull/2338))

Project.toml

@@ -9,6 +9,7 @@ DataAPI = "9a962f9c-6df0-11e9-0e5d-c546b8b5ee8a"
 Future = "9fa8497b-333b-5362-9e8d-4d0656e87820"
 InvertedIndices = "41ab1584-1d38-5bbf-9106-f11c6c58b48f"
 IteratorInterfaceExtensions = "82899510-4779-5014-852e-03e436cf321d"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Missings = "e1d29d7a-bbdc-5cf2-9ac0-f12de2c33e28"
 PooledArrays = "2dfb63ee-cc39-5dd5-95bd-886bf059d720"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"

docs/src/lib/functions.md

@@ -124,3 +124,8 @@ eachrow
 values
 pairs
 ```
+
+## Equality
+```@docs
+isapprox
+```

src/DataFrames.jl

@@ -5,6 +5,7 @@ using Reexport, SortingAlgorithms, Compat, Unicode, PooledArrays
 @reexport using CategoricalArrays, Missings, InvertedIndices
 using Base.Sort, Base.Order, Base.Iterators
 using TableTraits, IteratorInterfaceExtensions
+import LinearAlgebra: norm
 
 import DataAPI,
        DataAPI.All,

src/abstractdataframe/abstractdataframe.jl

@@ -410,6 +410,22 @@ function Base.isequal(df1::AbstractDataFrame, df2::AbstractDataFrame)
     return true
 end
 
+"""
+    isapprox(df1::AbstractDataFrame, df2::AbstractDataFrame;
+             rtol::Real=atol>0 ? 0 : √eps, atol::Real=0,
+             nans::Bool=false, norm::Function=norm)
+
+Inexact equality comparison. `df1` and `df2` must have the same size and column names.
+Return  `true` if `isapprox` with given keyword arguments
+applied to all pairs of columns stored in `df1` and `df2` returns `true`.
+"""
+function Base.isapprox(df1::AbstractDataFrame, df2::AbstractDataFrame;
+                       atol::Real=0, rtol::Real=atol>0 ? 0 : √eps(),
+                       nans::Bool=false, norm::Function=norm)
+    size(df1) == size(df2) || throw(DimensionMismatch("dimensions must match: a has dims $(size(df1)), b has dims $(size(df2))"))
+    isequal(index(df1), index(df2)) || throw(ArgumentError("column names of passed data frames do not match"))
+    return all(isapprox.(eachcol(df1), eachcol(df2), atol=atol, rtol=rtol, nans=nans, norm=norm))
+end
 ##############################################################################
 ##
 ## Description

test/constructors.jl

@@ -223,6 +223,8 @@ end
     @test size(df, 1) == 3
     @test size(df, 2) == 2
     @test isequal(df, DataFrame(x1 = [0.0, 0.0, 0.0], x2 = [1.0, 1.0, 1.0]))
+    @test isapprox(df, DataFrame(x1 = [0.0, 0.0, 0.0], x2 = [1.0, 1.0, 1.0]))
+    @test isapprox(df, DataFrame(x1 = [0.0, 0.0, 0.0], x2 = [1.000000010000, 1.0, 1.0]))
 
     df = DataFrame(:type => [], :begin => [])
     @test propertynames(df) == [:type, :begin]