# How to add line for indicating mean on histogram?

**URL:** <https://discourse.julialang.org/t/how-to-add-line-for-indicating-mean-on-histogram/103444>\
**Category:** New to Julia\
**Tags:** question, plotting, plot\
**Created:** [September 1, 2023, 12:57pm UTC](https://discourse.julialang.org/t/how-to-add-line-for-indicating-mean-on-histogram/103444 "2023-09-01T12:57:51Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Sahil\_Khan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sahil_khan/32/47573_2.png) [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Post date:** [September 1, 2023, 12:57pm UTC](https://discourse.julialang.org/t/how-to-add-line-for-indicating-mean-on-histogram/103444/1 "2023-09-01T12:57:51Z")

</div>

I have this histogram and want to add a vline to show mean value or median value. `vline!(some_value)`. is not working.

 ![image](https://global.discourse-cdn.com/julialang/original/3X/c/b/cb44c8db5c503930a735bbde07805223e868ec03.png)

I get this error.

````julia
ERROR: Cannot convert Float64 to series data for plotting
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] _prepare_series_data(x::Float64)
    @ RecipesPipeline ~/.julia/packages/RecipesPipeline/BGM3l/src/series.jl:8
  [3] _series_data_vector(x::Float64, plotattributes::Dict{Symbol, Any})
    @ RecipesPipeline ~/.julia/packages/RecipesPipeline/BGM3l/src/series.jl:36
  [4] macro expansion
    @ ~/.julia/packages/RecipesPipeline/BGM3l/src/series.jl:129 [inlined]
  [5] apply_recipe(plotattributes::AbstractDict{Symbol, Any}, #unused#::Type{RecipesPipeline.SliceIt}, x::Any, y::Any, z::Any)
    @ RecipesPipeline ~/.julia/packages/RecipesBase/BRe07/src/RecipesBase.jl:300
  [6] _process_userrecipes!(plt::Any, plotattributes::Any, args::Any)
    @ RecipesPipeline ~/.julia/packages/RecipesPipeline/BGM3l/src/user_recipe.jl:38
  [7] recipe_pipeline!(plt::Any, plotattributes::Any, args::Any)
    @ RecipesPipeline ~/.julia/packages/RecipesPipeline/BGM3l/src/RecipesPipeline.jl:72
  [8] _plot!(plt::Plots.Plot, plotattributes::Any, args::Any)
    @ Plots ~/.julia/packages/Plots/3BCH5/src/plot.jl:223
  [9] plot!(plt::Plots.Plot, args::Any; kw::Base.Pairs{Symbol, V, Tuple{Vararg{Symbol, N}}, NamedTuple{names, T}} where {V, N, names, T<:Tuple{Vararg{Any, N}}})
    @ Plots ~/.julia/packages/Plots/3BCH5/src/plot.jl:213
 [10] plot!(args::Any; kw::Base.Pairs{Symbol, V, Tuple{Vararg{Symbol, N}}, NamedTuple{names, T}} where {V, N, names, T<:Tuple{Vararg{Any, N}}})
    @ Plots ~/.julia/packages/Plots/3BCH5/src/plot.jl:202
 [11] vline!(args::Any; kw::Base.Pairs{Symbol, V, Tuple{Vararg{Symbol, N}}, NamedTuple{names, T}} where {V, N, names, T<:Tuple{Vararg{Any, N}}})
    @ Plots ~/.julia/packages/RecipesBase/BRe07/src/RecipesBase.jl:429
 [12] vline!(args::Any)
    @ Plots ~/.julia/packages/RecipesBase/BRe07/src/RecipesBase.jl:429
 [13] top-level scope
    @ REPL[127]:1```
````

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<div class="post-metadata">

**Author:** ![skleinbo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/skleinbo/32/36080_2.png) [@skleinbo](https://discourse.julialang.org/u/skleinbo)\
**Post date:** [September 1, 2023, 1:08pm UTC](https://discourse.julialang.org/t/how-to-add-line-for-indicating-mean-on-histogram/103444/2 "2023-09-01T13:08:27Z")

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Try

```julia
vline!([some_value])

```

vline and hline want arrays of values if I’m not mistaken.

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<div class="post-metadata">

**Author:** ![Sahil\_Khan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sahil_khan/32/47573_2.png) [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Post date:** [September 1, 2023, 1:24pm UTC](https://discourse.julialang.org/t/how-to-add-line-for-indicating-mean-on-histogram/103444/3 "2023-09-01T13:24:00Z")

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Thank you…it works now… 🙂