# PyPlot: how to include a variable in a title

**URL:** <https://discourse.julialang.org/t/pyplot-how-to-include-a-variable-in-a-title/41121>\
**Category:** New to Julia\
**Tags:** pyplot\
**Created:** [June 10, 2020, 11:29am UTC](https://discourse.julialang.org/t/pyplot-how-to-include-a-variable-in-a-title/41121 "2020-06-10T11:29:48Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![fusion809](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fusion809/32/6080_2.png) [@fusion809](https://discourse.julialang.org/u/fusion809)\
**Post date:** [June 10, 2020, 11:29am UTC](https://discourse.julialang.org/t/pyplot-how-to-include-a-variable-in-a-title/41121/1 "2020-06-10T11:29:48Z")

</div>

Hi,

I have this loop in my code:

```julia
for i=1:30
    PyPlot.figure(i)
    if i < 3
        PyPlot.plot(y[1:801],eigenfunction_approx[1:801,i])
        PyPlot.title("Plot of the ${i}th eigenfunction")
    elseif i < 10
        PyPlot.plot(y[1:1001],eigenfunction_approx[1:1001,i])
        PyPlot.title("Plot of the ${i}th eigenfunction")
    else
        PyPlot.plot(y[1:1301],eigenfunction_approx[1:1301,i])
        PyPlot.title("Plot of the ${i}th eigenfunction")
    end
end

```

I’d like the title to include the number of the eigenfunction being displayed, which in this loop is i. How do I do that? The only docs for the Julia PyPlot module I’ve found is its README and it doesn’t mention how one would do this. I’ve tried using `PyPlot.title("Plot of the ", i, "th eigenfunction")` as I thought maybe it might work like Python does and I’d expect something like that to work in Python. If you’d like the error I got from that it’s:

```julia
PyError ($(Expr(:escape, :(ccall(#= /home/fusion809/.julia/packages/PyCall/zqDXB/src/pyfncall.jl:43 =# @pysym(:PyObject_Call), PyPtr, (PyPtr, PyPtr, PyPtr), o, pyargsptr, kw))))) <class 'ValueError'>
ValueError("'th eigenfunction' is not a valid value for loc; supported values are 'left', 'center', 'right'")
  File "/usr/lib/python3.8/site-packages/matplotlib/pyplot.py", line 3031, in title
    return gca().set_title(
  File "/usr/lib/python3.8/site-packages/matplotlib/axes/_axes.py", line 198, in set_title
    title = cbook._check_getitem(titles, loc=loc.lower())
  File "/usr/lib/python3.8/site-packages/matplotlib/cbook/ __init__.py", line 2165, in _check_getitem
    raise ValueError(

```

and from my loop above I got:

```julia
syntax: invalid interpolation syntax: "${"

```

I’m just hoping one of you good folks knows the answer to this problem.

Thanks for your time

---

<div class="post-metadata">

**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [June 10, 2020, 12:12pm UTC](https://discourse.julialang.org/t/pyplot-how-to-include-a-variable-in-a-title/41121/2 "2020-06-10T12:12:29Z")

</div>

> [@fusion809](#):
>
> `PyPlot.title("Plot of the ${i}th eigenfunction")`

You want `PyPlot.title("Plot of the $(i)th eigenfunction")`.

This has nothing to do with PyPlot specifically. This is how you do [string interpolation in Julia](https://docs.julialang.org/en/latest/manual/strings/#string-interpolation-1).