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Function Signature

plot(x, y, ...)

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Description

Plot methods for Intensity objects based on Intensity Analysis output. The plot() function is an S4 method with specialized implementations for three different object types: Interval, Category, and Transition. Each plot type visualizes a different level of the intensity analysis, creating publication-ready graphics that help interpret land use and cover change patterns.

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Methods

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Interval Level Plot

plot(
  x,
  y,
  labels = c(
    leftlabel = "Interval Change Area (percent of map)",
    rightlabel = "Annual Change Area (percent of map)"
  ),
  title = NA,
  labs = c(type = "Changes", ur = "Uniform Intensity"),
  marginplot = c(lh = -10, rh = 0),
  leg_curv = c(x = 0.1, y = 0.1),
  color_bar = c(fast = "#B22222", slow = "#006400", area = "gray40"),
  fontsize_ui = 10,
  ...
)
Plots the interval level analysis showing how the size and speed of change vary across time intervals.

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Category Level Plot

plot(
  x,
  y,
  labels = c(
    leftlabel = "Annual Change Area (km2 or pixels)",
    rightlabel = "Annual Change Intensity (percent of category)"
  ),
  title = NA,
  labs = c(type = "Categories", ur = "Uniform Intensity"),
  marginplot = c(lh = 0.5, rh = 0.5),
  leg_curv = c(x = 0.1, y = 0.1),
  fontsize_ui = 10,
  ...
)
Plots the category level analysis showing gross losses or gross gains for each category.

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Transition Level Plot

plot(
  x,
  y,
  labels = c(
    leftlabel = "Annual Transition Area (km2 or pixels)",
    rightlabel = "Annual Transition Intensity (percent of category)"
  ),
  title = NA,
  labs = c(type = "Categories", ur = "Uniform Intensity"),
  marginplot = c(lh = 0.5, rh = 0.5),
  leg_curv = c(x = 0.1, y = 0.1),
  fontsize_ui = 10,
  ...
)
Plots the transition level analysis showing transitions to or from a specific category.

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Parameters

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x
Interval | Category | Transition
required
An intensity object generated by intensityAnalysis(). The type of object determines which plot method is called:
  • Interval object: plots interval level analysis
  • Category object: plots category level analysis (gain or loss)
  • Transition object: plots transition level analysis (gain or loss)
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y
any
Ignored. Included for S4 method compatibility.
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labels
character vector
Left and right axis titles (captions). Provide as a named vector:
  • leftlabel: Title for the left axis (typically area values)
  • rightlabel: Title for the right axis (typically intensity values)
Default values vary by plot type.
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title
character
default:"NA"
Main title for the plot. If NA (default), no title is displayed.
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labs
character vector
Legend labels. Provide as a named vector:
  • type: Label for the category/change type legend
  • ur: Label for the uniform intensity reference line
Defaults vary by plot type.
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marginplot
numeric vector
Adjustment of the origins of left and right parts of the plots. Provide as a named vector:
  • lh: Left margin adjustment (in points)
  • rh: Right margin adjustment (in points)
Defaults vary by plot type. Use negative values to bring panels closer together.
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leg_curv
numeric vector
X and Y values that control the arrow size and position pointing to the Uniform Intensity vertical line. Provide as a named vector:
  • x: Horizontal offset for the arrow endpoint
  • y: Vertical offset for the arrow endpoint
Default: c(x = 0.1, y = 0.1)
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color_bar
character vector
Colors defined for the fast, slow, and area bars. Only applicable for Interval objects. Provide as a named vector:
  • fast: Color for fast change intervals (default: "#B22222" - firebrick red)
  • slow: Color for slow change intervals (default: "#006400" - dark green)
  • area: Color for area bars (default: "gray40")
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fontsize_ui
numeric
default:"10"
Font size of the uniform intensity percentage label in the plot.
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...
additional arguments
Additional arguments passed to ggplot2::theme() for further plot customization. See ggplot2::theme() documentation for available options.

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Return Value

Returns an intensity graph as a grid object, which is automatically displayed. The plot uses ggplot2 and gridExtra for rendering.

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Examples

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Plotting Interval Level Analysis

# Perform intensity analysis
result <- intensityAnalysis(
  dataset = SL_2002_2014,
  category_n = "Ap",
  category_m = "SG",
  area_km2 = TRUE
)

# Plot interval level with default settings
plot(result$interval_lvl)

# Plot with custom title and labels
plot(
  result$interval_lvl,
  title = "Interval Level Intensity Analysis",
  labels = c(
    leftlabel = "Interval Change (%)",
    rightlabel = "Annual Change (%)"
  )
)

# Customize colors and appearance
plot(
  result$interval_lvl,
  color_bar = c(fast = "red", slow = "blue", area = "gray"),
  fontsize_ui = 12
)

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Plotting Category Level Analysis

# Plot category level gains
plot(result$category_lvlGain)

# Plot category level losses with custom title
plot(
  result$category_lvlLoss,
  title = "Category Level: Losses",
  labs = c(type = "Land Categories", ur = "Uniform Rate")
)

# Adjust margins for better spacing
plot(
  result$category_lvlGain,
  marginplot = c(lh = 1, rh = 1)
)

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Plotting Transition Level Analysis

# Plot transition level gains (transitions TO category_n)
plot(result$transition_lvlGain_n)

# Plot transition level losses (transitions FROM category_m)
plot(result$transition_lvlLoss_m)

# Customize arrow position and font size
plot(
  result$transition_lvlGain_n,
  leg_curv = c(x = 0.15, y = 0.2),
  fontsize_ui = 11
)

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Advanced Customization with ggplot2 Theme

# Pass additional theme arguments for fine-tuned control
plot(
  result$interval_lvl,
  title = "Land Change Intensity Over Time",
  axis.text = element_text(size = 10),
  axis.title = element_text(size = 12, face = "bold"),
  legend.position = "bottom",
  panel.background = element_rect(fill = "white")
)

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Understanding the Plots

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Interval Level Plots

Interval level plots show:
  • Left panel: Total change area for each time interval
  • Right panel: Annual intensity of change with a uniform intensity reference line
  • Colors: Fast (above uniform) vs. slow (below uniform) change rates

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Category Level Plots

Category level plots show:
  • Left panel: Gross gain or loss area for each category
  • Right panel: Annual intensity of gain or loss with uniform intensity reference
  • Facets: Separate panels for each time interval
  • Colors: Category-specific colors from the legend

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Transition Level Plots

Transition level plots show:
  • Left panel: Transition area to/from the target category
  • Right panel: Transition intensity with uniform intensity reference
  • Facets: Separate panels for each time interval
  • Interpretation: Categories above the uniform line are “targeted” or “targeting”; those below are “avoided” or “avoiding”

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See Also

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