# Can't get a basic plot to work (Gadfly

**URL:** <https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510>\
**Category:** New to Julia\
**Tags:** question, plotting\
**Created:** [February 12, 2023, 1:01pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510 "2023-02-12T13:01:31Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tim\_Booher](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tim_booher/32/24148_2.png) [@Tim\_Booher](https://discourse.julialang.org/u/Tim_Booher)\
**Post date:** [February 12, 2023, 1:01pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/1 "2023-02-12T13:01:31Z")

</div>

I think I’m using too many libraries and I can’t get two lines on the same plot.

```julia
using Pkg
Pkg.add("DataFrames")
Pkg.add("Gadfly")
Pkg.add("Dates")
Pkg.add("StatsBase")
Pkg.add("Query")
Pkg.add("Polynomials")
Pkg.add("Missings")

using DataFrames, Gadfly, Dates, LibPQ, StatsBase, Query, Polynomials

using Missings

# Connect to the database
conn = LibPQ.Connection("postgresql://postgres:mypw@localhost:5433/financials")

# Execute the SQL query to retrieve the data
df = DataFrames.DataFrame(execute(conn, """
    SELECT "Date", "Amount", "Cat2"
    FROM "2022_finances"
    WHERE "Cat1" = 'Income'
"""))

# Close the connection
close(conn)

# Convert the 'Date' column to a DateTime object
df.Date = Dates.DateTime.(df.Date)

grouped = df |>
    @groupby(month(_.Date)) |>
    @map({Month=key(_), Amount=sum(_.Amount)}) |>
    DataFrame

# Generate the extrapolation
grouped.Month = convert(Array{Float64,1}, grouped.Month)
x = coalesce.(grouped.Month)
y = coalesce.(grouped.Amount)
p = Polynomials.fit(x, y, 3) # can't get this work without the parent class

x_float = convert(Array{Float64, 1}, collect(13:24))
y_float = p.(x_float)

# Plot the data
df_extrapolation = DataFrame(Month=x_float, Amount=y_float)
x = df_extrapolation[!, :Month]
y = df_extrapolation[!, :Amount]

p = plot()
# Plot the original data
plot(grouped, x=:Month, y=coalesce.(:Amount), Geom.line(),
Guide.xlabel("Month"), Guide.ylabel("Amount (\$)"))

# Plot the extrapolation
plot!(df_extrapolation, x=:Month, y=:Amount, Geom.line(), label="Extrapolation")

```

ERROR: Cannot convert DataFrame to series data for plotting  
I’ve tried so many different inputs and can’t the plots to combine.

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 12, 2023, 2:16pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/2 "2023-02-12T14:16:47Z")

</div>

Could you provide a minimal set of data for the dataframe `df` ?

---

<div class="post-metadata">

**Author:** ![Tim\_Booher](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tim_booher/32/24148_2.png) [@Tim\_Booher](https://discourse.julialang.org/u/Tim_Booher)\
**Post date:** [February 12, 2023, 2:24pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/3 "2023-02-12T14:24:49Z")

</div>

Yes.  
df is:  
246×3 DataFrame  
Row │ Date Amount Cat2  
│ DateTime Float64? String?  
─────┼──────────────────────────────────────────────  
1 │ 2022-01-27T00:00:00 1036.61 Tim  
2 │ 2022-03-31T00:00:00 1500.0 John  
3 │ 2022-04-28T00:00:00 1500.0 John  
4 │ 2022-05-31T00:00:00 1500.0 John

Grouped is something like:  
12×2 DataFrame  
Row │ Month Amount  
│ Float64 Float64?  
─────┼────────────────────────  
1 │ 1.0 146.3  
2 │ 3.0 134.2  
3 │ 4.0 240.7  
4 │ 5.0 348.7

Super appreciative of your help.

---

<div class="post-metadata">

**Author:** ![Tim\_Booher](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tim_booher/32/24148_2.png) [@Tim\_Booher](https://discourse.julialang.org/u/Tim_Booher)\
**Post date:** [February 12, 2023, 2:30pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/4 "2023-02-12T14:30:23Z")

</div>

I’m wondering if something like this would be a better approach:

```julia
using DataFrames, Dates, TimeSeries

# Load the data set into a DataFrame
df = DataFrame(Date = DateTime[DateTime("2022-01-27T00:00:00"),
                                DateTime("2022-03-31T00:00:00"),
                                DateTime("2022-04-28T00:00:00"),
                                DateTime("2022-05-31T00:00:00")],
               Amount = [1036.61, 1500.0, 1500.0, 1500.0],
               Cat2 = ["Tim", "Rentals", "Rentals", "Rentals"])

# Convert the Date column to a TimeArray
t = TimeArray(df.Date, df.Amount)

# Fit an ARIMA model to the time series
model = fit(ARIMA, t)

# Generate forecasts for the next 6 months
forecast = forecast(model, 6)

# Plot the historical data and the forecast
using Plots
plot(t, label = "Historical Data")
plot!(forecast, label = "Forecast")

# Add uncertainty bands to the forecast
fcast_mean, fcast_lower, fcast_upper = fcast(model, 6, 0.95)
fill!(fcast_mean, fcast_lower, fcast_upper, alpha = 0.3)
plot!(fcast_mean, fill = (0, :gray), label = "Uncertainty Band")

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 12, 2023, 3:19pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/5 "2023-02-12T15:19:57Z")

</div>

> [@Tim\_Booher](#):
>
> ERROR: Cannot convert DataFrame to series data for plotting  
> I’ve tried so many different inputs and can’t the plots to combine.

Just on your first issue, I think you are mixing up some plotting packages, e.g. `plot!` is not part of Gadfly (you probably have a `using Plots` in your REPLs history).

Be sure, that your REPL is clean, by starting a new one.

Composing a plot with several data in Gadfly you use layers, see [Compositing · Gadfly.jl](http://gadflyjl.org/stable/man/compositing/#Layers)

You original code with the example data you provided would look like:

```julia
using DataFrames, Gadfly, Dates, LibPQ, StatsBase, Query, Polynomials

using Missings

# Connect to the database
#conn = LibPQ.Connection("postgresql://postgres:mypw@localhost:5433/financials")
# Execute the SQL query to retrieve the data
#df = DataFrames.DataFrame(execute(conn, """
# SELECT "Date", "Amount", "Cat2"
# FROM "2022_finances"
# WHERE "Cat1" = 'Income'
#"""))
# Close the connection
#close(conn)
# Convert the 'Date' column to a DateTime object
#df.Date = Dates.DateTime.(df.Date)

df=DataFrame(
    "Date" => Dates.DateTime.(["2022-01-27T00:00:00", "2022-03-31T00:00:00", "2022-04-28T00:00:00", "2022-05-31T00:00:00"]), 
    "Amount" => [1036.61, 1500.0, 1500.0, 1500.0], 
    "Cat2" => ["Tim", "John", "John", "John"])

grouped = df |>
    @groupby(month(_.Date)) |>
    @map({Month=key(_), Amount=sum(_.Amount)}) |>
    DataFrame

# Generate the extrapolation
grouped.Month = convert(Array{Float64,1}, grouped.Month)
x = coalesce.(grouped.Month)
y = coalesce.(grouped.Amount)
p = Polynomials.fit(x, y, 3) # can't get this work without the parent class

x_float = convert(Array{Float64, 1}, collect(13:24))
y_float = p.(x_float)

# Plot the data
df_extrapolation = DataFrame(Month=x_float, Amount=y_float)
x = df_extrapolation[!, :Month]
y = df_extrapolation[!, :Amount]

p1=layer(grouped, x=:Month, y=coalesce.(:Amount), Geom.line())
p2=layer(df_extrapolation, x=:Month, y=:Amount, Geom.line())
plot(p1,p2,Guide.xlabel("Month"), Guide.ylabel("Amount (\$)"))

```

It’s not so nice because of the limited number of samples in the example and you would use some colors for the different layers.

> [@Tim\_Booher](#):
>
> I’m wondering if something like this would be a better approach:

I am ignoring that new issue as it overloads me for now, but again it looks like the Plots package and not Gadfly. Same advice: clean REPL and decide on one plotting package. Both are great!

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<div class="post-metadata">

**Author:** ![Tim\_Booher](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tim_booher/32/24148_2.png) [@Tim\_Booher](https://discourse.julialang.org/u/Tim_Booher)\
**Post date:** [February 12, 2023, 10:23pm UTC](https://discourse.julialang.org/t/cant-get-a-basic-plot-to-work-gadfly/94510/6 "2023-02-12T22:23:35Z")

</div>

That is super helpful. Thanks. That makes sense now and explains why I was so confused.