Merge pull request #39 from BigThinkcode/step_plot

Step plot

Author: Sadique-The-Alchemist

lib/matplotex.ex

@@ -588,6 +588,23 @@ defmodule Matplotex do
     Spline.create(figure, {x, y}, opts)
   end
 
+  @doc """
+  Creates a step plot with the given parameters
+  ## Parameters
+
+  - `x` (list): A list of x-coordinates for the data points.
+  - `y` (list): A list of y-coordinates corresponding to the x-coordinates.
+  ```elixir
+   x = [1,2,3,4,5]
+   y = [1,4,9,16,25]
+   Matplotex.step(x, y, color: "blue")
+   |>Matplotex.set_xlabel("Numbers")
+   |>Matplotex.set_ylabel("Squares")
+  ```
+  """
+  def step(x, y, opts), do: Matplotex.Figure.Areal.Step.create(x, y, opts)
+  def step(figure, x, y, opts), do: Matplotex.Figure.Areal.Step.create(figure, x, y, opts)
+
   @doc """
   Sets X labels for the graph with given font details
 
@@ -597,7 +614,6 @@ defmodule Matplotex do
       %Matplotex.Figure{}
 
   """
-
   @spec set_xlabel(Figure.t(), String.t()) :: Figure.t()
   def set_xlabel(figure, label, opts \\ []) do
     Figure.add_label(figure, {:x, label}, opts)

lib/matplotex/figure/areal/step.ex

@@ -0,0 +1,37 @@
+defmodule Matplotex.Figure.Areal.Step do
+
+  alias Matplotex.Figure.Areal.LinePlot
+  alias Matplotex.Figure
+  alias Matplotex.InputError
+
+  def create(x, y, opts) do
+    {x, y} = step_segments(x, y)
+    LinePlot.create(%Figure{axes: %LinePlot{}}, {x, y}, opts)
+   end
+   def create(%Figure{} = figure, x, y, opts) do
+     {x, y} = step_segments(x, y)
+     LinePlot.create(figure, {x, y}, opts)
+   end
+   defp step_segments(x, y) do
+     x = horizontal_segments(x)
+     y = vertical_segments(y)
+     {x,y}
+   end
+   defp horizontal_segments(data) when is_list(data) do
+     first_value = List.first(data)
+     second_last_index = length(data) - 1
+     repeated = data|>Enum.slice(1..second_last_index)|>List.duplicate(2)|> List.flatten()
+     [first_value | repeated]|>Enum.sort()
+   end
+   defp horizontal_segments(_data), do: list_error(:y)
+
+   defp vertical_segments(data) when is_list(data) do
+     data|>List.duplicate(2)|>List.flatten()|>Enum.sort()
+   end
+   defp vertical_segments(_data), do: list_error(:y)
+
+   defp list_error(arg) do
+      raise InputError, message: "Expected a list for arg: #{arg}"
+   end
+
+end

test/matplotex_test.exs

@@ -304,4 +304,17 @@ defmodule MatplotexTest do
       assert data1.y == y
     end
   end
+
+  describe "step" do
+    test "creates a figure for step plot" do
+      x = [1, 2, 3, 4, 5]
+      y = [1,4,9,16,25]
+      assert %Figure{axes: %{dataset: [data1], label: label}} =
+        Matplotex.step(x, y, x_label: "X", y_label: "Y")
+        assert label.x == "X"
+        assert label.y == "Y"
+        assert data1.x|>Enum.uniq() == x
+        assert data1.y|>Enum.uniq() == y
+    end
+  end
 end