Add svyby functionality for svymean

src/Survey.jl

@@ -20,11 +20,13 @@ include("svyhist.jl")
 include("svyplot.jl")
 include("dimnames.jl")
 include("svyboxplot.jl")
+include("svyby.jl")
 
 export load_data
 export AbstractSurveyDesign, SimpleRandomSample, StratifiedSample
 export svydesign
 export svyglm
+export svyby
 export dim, colnames, dimnames
 export svymean, svytotal, svyquantile
 export @formula

src/svyby.jl

@@ -0,0 +1,38 @@
+"""
+The `svyby` function can be used to generate subsets of a survey design.
+
+```jldoctest
+julia> using Survey
+
+julia> apisrs = load_data("apisrs");
+
+julia> srs = SimpleRandomSample(apisrs);
+
+julia> svyby(:api00, :cname, srs, svytotal)
+38×2 DataFrame
+ Row │ cname            total
+     │ String15         Float64
+─────┼──────────────────────────
+   1 │ Kern              5736.0
+   2 │ Los Angeles      29617.0
+   3 │ Orange            6744.0
+   4 │ San Luis Obispo    739.0
+   5 │ San Francisco     1675.0
+   6 │ Modoc              671.0
+   7 │ Alameda           7437.0
+   8 │ Solano            1869.0
+  ⋮  │        ⋮            ⋮
+  32 │ Kings              939.0
+  33 │ Shasta            1508.0
+  34 │ Yolo               475.0
+  35 │ Calaveras          790.0
+  36 │ Napa              1454.0
+  37 │ Lake               804.0
+  38 │ Merced             595.0
+                 23 rows omitted
+```
+"""
+function svyby(formula::Symbol, by::Symbol, design::AbstractSurveyDesign, func::Function, params = [])
+    gdf = groupby(design.data, by)
+    return combine(gdf, [formula ] => ((a) -> func(a , design ,params...)) => AsTable)
+end

src/svymean.jl

@@ -18,10 +18,22 @@ function var_of_mean(x::Symbol, design::SimpleRandomSample)
     return design.fpc / design.sampsize * var(design.data[!, x])
 end
 
+function var_of_mean(x::AbstractVector, design::SimpleRandomSample)
+    return design.fpc / design.sampsize * var(x)
+end
+
 function sem(x, design::SimpleRandomSample)
     return sqrt(var_of_mean(x, design))
 end
 
+function sem(x::AbstractVector, design::SimpleRandomSample)
+    return sqrt(var_of_mean(x, design))
+end
+
 function svymean(x, design::SimpleRandomSample)
     return DataFrame(mean = mean(design.data[!, x]), sem = sem(x, design::SimpleRandomSample))
 end
+
+function svymean(x::AbstractVector , design::SimpleRandomSample)
+    return DataFrame(mean = mean(x), sem = sem(x, design::SimpleRandomSample))
+end