diff --git a/README.md b/README.md
index eaf6fb5..d16befb 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,11 @@
 # MetidaBase.jl
 
+
+[![Tier 1](https://github.com/PharmCat/MetidaBase.jl/actions/workflows/Tier1.yml/badge.svg)](https://github.com/PharmCat/MetidaBase.jl/actions/workflows/Tier1.yml)
+
+[![codecov](https://codecov.io/gh/PharmCat/MetidaBase.jl/branch/main/graph/badge.svg?token=C6D0R654F9)](https://codecov.io/gh/PharmCat/MetidaBase.jl)
+
+
 Metida base package.
 
 Used for:
diff --git a/src/MetidaBase.jl b/src/MetidaBase.jl
index 5426cc6..1068074 100644
--- a/src/MetidaBase.jl
+++ b/src/MetidaBase.jl
@@ -11,10 +11,11 @@ module MetidaBase
     import StatsModels: StatisticalModel
     import Tables: istable, columnaccess, columns, getcolumn, columnnames
 
-    import Base: getindex, length, ht_keyindex, show, pushfirst!, iterate
+    import Base: getindex, length, ht_keyindex, show, pushfirst!, iterate, size
 
     include("abstracttype.jl")
     include("types.jl")
     include("utils.jl")
+    include("iterators.jl")
 
 end
diff --git a/src/iterators.jl b/src/iterators.jl
new file mode 100644
index 0000000..b8d7db4
--- /dev/null
+++ b/src/iterators.jl
@@ -0,0 +1,69 @@
+################################################################################
+struct SkipNonPositive{T}
+    x::T
+end
+skipnonpositive(itr) = SkipNonPositive(itr)
+
+Base.IteratorEltype(::Type{SkipNonPositive{T}}) where {T} = Base.IteratorEltype(T)
+#Base.eltype(::Type{SkipNonPositive{T}}) where {T} = nonmissingtype(eltype(T))
+function Base.iterate(itr::SkipNonPositive, state...)
+    y = iterate(itr.x, state...)
+    y === nothing && return nothing
+    item, state = y
+    while !ispositive(item)
+        y = iterate(itr.x, state)
+        y === nothing && return nothing
+        item, state = y
+    end
+    item, state
+end
+Base.IndexStyle(::Type{<:SkipNonPositive{T}}) where {T} = IndexStyle(T)
+Base.eachindex(itr::SkipNonPositive) =
+    Iterators.filter(i -> ispositive(@inbounds(itr.x[i])), eachindex(itr.x))
+Base.keys(itr::SkipNonPositive) =
+    Iterators.filter(i -> ispositive(@inbounds(itr.x[i])), keys(itr.x))
+Base.@propagate_inbounds function getindex(itr::SkipNonPositive, I...)
+    v = itr.x[I...]
+    !ispositive(v) && throw(ErrorException("the value at index $I is non positive"))
+    v
+end
+function Base.length(itr::SkipNonPositive)
+    n = 0
+    for i in itr n+=1 end
+    n
+end
+################################################################################
+struct SkipNaNorMissing{T}
+    x::T
+end
+skipnanormissing(itr) = SkipNaNorMissing(itr)
+
+Base.IteratorEltype(::Type{SkipNaNorMissing{T}}) where {T} = Base.IteratorEltype(T)
+#Base.eltype(::Type{SkipNaNorMissing{T}}) where {T} = nonmissingtype(eltype(T))
+function Base.iterate(itr::SkipNaNorMissing, state...)
+    y = iterate(itr.x, state...)
+    y === nothing && return nothing
+    item, state = y
+    while isnanormissing(item)
+        y = iterate(itr.x, state)
+        y === nothing && return nothing
+        item, state = y
+    end
+    item, state
+end
+Base.IndexStyle(::Type{<:SkipNaNorMissing{T}}) where {T} = IndexStyle(T)
+Base.eachindex(itr::SkipNaNorMissing) =
+    Iterators.filter(i -> isnanormissing(@inbounds(itr.x[i])), eachindex(itr.x))
+Base.keys(itr::SkipNaNorMissing) =
+    Iterators.filter(i -> isnanormissing(@inbounds(itr.x[i])), keys(itr.x))
+Base.@propagate_inbounds function getindex(itr::SkipNaNorMissing, I...)
+    v = itr.x[I...]
+    !isnanormissing(v) && throw(ErrorException("The value at index $I is NaN or missing!"))
+    v
+end
+function Base.length(itr::SkipNaNorMissing)
+    n = 0
+    for i in itr n+=1 end
+    n
+end
+################################################################################
diff --git a/src/types.jl b/src/types.jl
index 0ab1087..a8dfbab 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -74,6 +74,16 @@ function Base.pushfirst!(t::MetidaTable, row::NamedTuple)
     t
 end
 
+function Base.size(t::MetidaTable, i::Int)
+    if i == 1
+        return length(t.table[1])
+    elseif i == 2
+        return length(t.table)
+    else
+        error("Wrong dimention!")
+    end
+end
+
 function Base.show(io::IO, table::MetidaTable)
     pretty_table(io, table; tf = PrettyTables.tf_compact)
 end
diff --git a/src/utils.jl b/src/utils.jl
index b5eb963..6c538a1 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -17,9 +17,19 @@ function sortbyvec!(a, vec)
     sort!(a, by = x -> findfirst(y -> x == y, vec))
 end
 
+################################################################################
+################################################################################
+
 isnanormissing(x::Number) = isnan(x)
+isnanormissing(x::AbstractFloat) = isnan(x) 
 isnanormissing(x::Missing) = true
 
+ispositive(::Missing) = false
+ispositive(x::AbstractFloat) = isnan(x) ? false : x > zero(x)
+ispositive(x) = x > zero(x)
+
+################################################################################
+################################################################################
 
 # STATISTICS
 
diff --git a/test/runtests.jl b/test/runtests.jl
index bf7382d..7199dab 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -14,6 +14,9 @@ using Test
     mt[:, :b]
     Base.show(io, mt)
 
+    @test size(mt, 1) == 5
+    @test size(mt, 2) == 2
+
     struct ExampleIDStruct <: MetidaBase.AbstractSubject
         #time
         #obs
@@ -51,6 +54,7 @@ using Test
     @test exrsds[:, :r1][1] == 3
     @test exrsds[1, :r1] == 3
 
+
     @test MetidaBase.getid(exidds[3], :a) == 2
     sort!(exidds, :a)
     @test MetidaBase.getid(exidds[3], :a) == 3
@@ -58,12 +62,22 @@ using Test
 
     sort!(exrsds, :a)
 
+    @test first(exrsds) == exrsds[1]
+
     MetidaBase.uniqueidlist(exidds, [:a])
     MetidaBase.uniqueidlist(exidds, :a)
 
     MetidaBase.subset(exidds, Dict(:a => 1))
-    #println(exrsds[:, :r1])
 
-    #println(MetidaBase.getid(exrsds, :, :a1))
+    mt = MetidaBase.metida_table(exrsds)
 
+    v1 = [1,2,-6,missing,NaN]
+    itr1 = MetidaBase.skipnanormissing(v1)
+    for i in itr1
+        @test !MetidaBase.isnanormissing(i)
+    end
+    itr2 = MetidaBase.skipnonpositive(v1)
+    for i in itr2
+        @test MetidaBase.ispositive(i)
+    end
 end