feat(ggplot2): implement acf-pacf

plots/acf-pacf/implementations/r/ggplot2.R

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+#' anyplot.ai
+#' acf-pacf: Autocorrelation and Partial Autocorrelation (ACF/PACF) Plot
+#' Library: ggplot2 3.5.1 | R 4.4.1
+#' Quality: 88/100 | Created: 2026-06-10
+
+library(ggplot2)
+library(ragg)
+
+set.seed(42)
+
+# Theme tokens — Imprint palette (see prompts/default-style-guide.md)
+THEME       <- Sys.getenv("ANYPLOT_THEME", "light")
+PAGE_BG     <- if (THEME == "light") "#FAF8F1" else "#1A1A17"
+ELEVATED_BG <- if (THEME == "light") "#FFFDF6" else "#242420"
+INK         <- if (THEME == "light") "#1A1A17" else "#F0EFE8"
+INK_SOFT    <- if (THEME == "light") "#4A4A44" else "#B8B7B0"
+INK_MUTED   <- if (THEME == "light") "#6B6A63" else "#A8A79F"
+
+IMPRINT_PALETTE <- c(
+  "#009E73",  # 1 — brand green (first series)
+  "#C475FD",  # 2 — lavender
+  "#4467A3",  # 3 — blue
+  "#BD8233",  # 4 — ochre
+  "#AE3030",  # 5 — matte red
+  "#2ABCCD",  # 6 — cyan
+  "#954477",  # 7 — rose
+  "#99B314"   # 8 — lime
+)
+
+# Data: synthetic AR(2) time series (n = 300 observations)
+# phi1 = 0.7, phi2 = -0.3 produces geometrically decaying ACF and PACF cutoff at lag 2
+ts_data <- arima.sim(model = list(ar = c(0.7, -0.3)), n = 300, sd = 0.5)
+n_obs   <- length(ts_data)
+n_lags  <- 36
+ci      <- 1.96 / sqrt(n_obs)
+
+# Compute ACF (lags 0–36) and PACF (lags 1–36)
+acf_out  <- acf(ts_data,  lag.max = n_lags, plot = FALSE)
+pacf_out <- pacf(ts_data, lag.max = n_lags, plot = FALSE)
+
+acf_df <- data.frame(
+  lag  = 0:n_lags,
+  corr = as.numeric(acf_out$acf),
+  type = "ACF"
+)
+pacf_df <- data.frame(
+  lag  = 1:n_lags,
+  corr = as.numeric(pacf_out$acf),
+  type = "PACF"
+)
+df      <- rbind(acf_df, pacf_df)
+df$type <- factor(df$type, levels = c("ACF", "PACF"))
+df$significant <- abs(df$corr) > ci
+
+plot_title <- "acf-pacf · r · ggplot2 · anyplot.ai"
+
+# Plot
+p <- ggplot(df, aes(x = lag, y = corr)) +
+  geom_hline(yintercept = 0,   color = INK_SOFT,  linewidth = 0.4) +
+  geom_hline(yintercept =  ci, color = INK_MUTED, linetype = "dashed", linewidth = 0.5) +
+  geom_hline(yintercept = -ci, color = INK_MUTED, linetype = "dashed", linewidth = 0.5) +
+  geom_segment(
+    aes(xend = lag, yend = 0, color = significant),
+    linewidth = 1.2
+  ) +
+  scale_color_manual(
+    values = c("TRUE" = IMPRINT_PALETTE[1], "FALSE" = INK_MUTED),
+    guide  = "none"
+  ) +
+  facet_wrap(~ type, ncol = 1, scales = "free_y") +
+  scale_x_continuous(breaks = seq(0, n_lags, by = 5)) +
+  labs(
+    x     = "Lag",
+    y     = "Autocorrelation",
+    title = plot_title
+  ) +
+  theme_minimal(base_size = 8) +
+  theme(
+    plot.background  = element_rect(fill = PAGE_BG,     color = PAGE_BG),
+    panel.background = element_rect(fill = PAGE_BG,     color = NA),
+    panel.grid.major = element_line(color = INK_SOFT,   linewidth = 0.2),
+    panel.grid.minor = element_blank(),
+    panel.border          = element_blank(),
+    axis.line.x.bottom    = element_line(color = INK_SOFT, linewidth = 0.4),
+    axis.line.y.left      = element_line(color = INK_SOFT, linewidth = 0.4),
+    axis.title       = element_text(color = INK,        size = 10),
+    axis.text        = element_text(color = INK_SOFT,   size = 8),
+    plot.title       = element_text(color = INK,        size = 12,
+                                    margin = margin(b = 8)),
+    strip.text       = element_text(color = INK,        size = 10, face = "bold"),
+    strip.background = element_rect(fill = ELEVATED_BG, color = INK_SOFT),
+    plot.margin      = margin(t = 12, r = 12, b = 12, l = 12)
+  )
+
+# Save
+ggsave(
+  filename = sprintf("plot-%s.png", THEME),
+  plot     = p,
+  device   = ragg::agg_png,
+  width    = 8,
+  height   = 4.5,
+  units    = "in",
+  dpi      = 400
+)

plots/acf-pacf/metadata/r/ggplot2.yaml

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+library: ggplot2
+language: r
+specification_id: acf-pacf
+created: '2026-06-10T01:54:24Z'
+updated: '2026-06-10T02:11:50Z'
+generated_by: claude-sonnet
+workflow_run: 27247629569
+issue: 4663
+language_version: 4.4.1
+library_version: 3.5.1
+preview_url_light: https://storage.googleapis.com/anyplot-images/plots/acf-pacf/r/ggplot2/plot-light.png
+preview_url_dark: https://storage.googleapis.com/anyplot-images/plots/acf-pacf/r/ggplot2/plot-dark.png
+preview_html_light: null
+preview_html_dark: null
+quality_score: 88
+review:
+  strengths:
+  - Significant-lag color coding (green=#009E73 vs gray INK_MUTED) elegantly tells
+    the ACF/PACF story at a glance
+  - Correct facet_wrap design with free_y scales and clearly labeled strips
+  - 'Full spec compliance: lag 0 in ACF, PACF from lag 1, correct CI formula, 36 lags'
+  - AR(2) synthetic data with phi1=0.7, phi2=-0.3 produces textbook-quality ACF/PACF
+    patterns
+  - 'Proper theme-adaptive chrome: L-shaped spines, subtle grid, ELEVATED_BG strip
+    backgrounds'
+  - 'Perfect code structure: KISS, set.seed(42), clean imports, correct linewidth
+    API'
+  weaknesses:
+  - Stem linewidth=1.2 is thin for a 3200x1800 canvas — non-significant bars are very
+    short and barely readable; increase to linewidth=1.6-2.0 for better visibility
+  - 'DE-01 could be stronger: the strip border (INK_SOFT on strip.background) creates
+    a noticeable box frame that is slightly heavy — consider element_rect(fill=ELEVATED_BG,
+    color=NA) to remove the border for a cleaner look'
+  - 'LM-02: the implementation does not exploit ggplot2 grammar beyond faceting +
+    geom_segment; consider using ggplot2-idiomatic stat_function or annotate for the
+    CI band to distinguish it from a plain geom_hline'
+  image_description: |-
+    Light render (plot-light.png):
+      Background: Warm off-white #FAF8F1 — correct Imprint light surface
+      Chrome: Title "acf-pacf · r · ggplot2 · anyplot.ai" in dark ink (#1A1A17) at top-left; Y-axis label "Autocorrelation" and X-axis label "Lag" in dark ink — all clearly readable. Tick labels in INK_SOFT (#4A4A44) at 8pt — readable. Facet strip labels "ACF" and "PACF" bold in dark ink on elevated cream (#FFFDF6) strip background with INK_SOFT border.
+      Data: Significant lags in brand green #009E73; non-significant lags in muted gray (INK_MUTED). Dashed CI lines in INK_MUTED. Lag 0 in ACF reaches 1.0 (green); lag 1 in ACF (~0.5) and lag 2 in ACF (~-0.13, just outside CI) are green; PACF shows lag 1 (~0.47) and lag 2 (~-0.30) as significant green. Grid lines subtle, L-shaped spines.
+      Legibility verdict: PASS — all text readable, no light-on-light issues
+
+    Dark render (plot-dark.png):
+      Background: Warm near-black #1A1A17 — correct Imprint dark surface
+      Chrome: Title in light ink (#F0EFE8) — clearly readable against dark background. Y and X axis labels in light ink. Tick labels in INK_SOFT (#B8B7B0) — clearly readable. Facet strips use ELEVATED_BG (#242420) with INK_SOFT border; strip text in light INK — readable. Grid lines in INK_SOFT at linewidth=0.2 — subtle white-ish lines visible against dark background.
+      Data: Significant lags identical brand green #009E73 — same as light render, correct. Non-significant lags in lighter gray (INK_MUTED #A8A79F). Dashed CI lines in lighter gray. All data colors identical to light render — only chrome flipped.
+      Legibility verdict: PASS — no dark-on-dark failures, all text readable against near-black background, brand green clearly visible
+  criteria_checklist:
+    visual_quality:
+      score: 27
+      max: 30
+      items:
+      - id: VQ-01
+        name: Text Legibility
+        score: 7
+        max: 8
+        passed: true
+        comment: 'All font sizes explicitly set (title=12, axis.title=10, axis.text=8,
+          strip.text=10); readable in both themes. Minor: stem linewidth=1.2 slightly
+          thin for canvas size but text is fine.'
+      - id: VQ-02
+        name: No Overlap
+        score: 6
+        max: 6
+        passed: true
+        comment: No overlapping text or data elements in either render
+      - id: VQ-03
+        name: Element Visibility
+        score: 4
+        max: 6
+        passed: true
+        comment: Significant stems clearly visible in green; non-significant stems
+          thin at linewidth=1.2 on a 3200x1800 canvas — visible but not optimally
+          sized for the resolution
+      - id: VQ-04
+        name: Color Accessibility
+        score: 2
+        max: 2
+        passed: true
+        comment: Green (#009E73) vs gray (INK_MUTED) is CVD-safe and clearly distinguishable
+          without relying on hue alone
+      - id: VQ-05
+        name: Layout & Canvas
+        score: 4
+        max: 4
+        passed: true
+        comment: Two-panel facet layout fills canvas well, balanced margins, no wasted
+          space
+      - id: VQ-06
+        name: Axis Labels & Title
+        score: 2
+        max: 2
+        passed: true
+        comment: 'Y-axis: ''Autocorrelation''; X-axis: ''Lag''; title matches required
+          format; facet strips label ACF/PACF panels'
+      - id: VQ-07
+        name: Palette Compliance
+        score: 2
+        max: 2
+        passed: true
+        comment: 'First/significant series uses #009E73; backgrounds #FAF8F1 (light)
+          / #1A1A17 (dark); data colors identical across themes; chrome theme-adaptive'
+    design_excellence:
+      score: 13
+      max: 20
+      items:
+      - id: DE-01
+        name: Aesthetic Sophistication
+        score: 5
+        max: 8
+        passed: true
+        comment: Intentional semantic color use (significant=green, non-significant=gray),
+          clean facet strips with elevated backgrounds — above defaults but not publication-ready
+      - id: DE-02
+        name: Visual Refinement
+        score: 4
+        max: 6
+        passed: true
+        comment: L-shaped spines, minor grid removed, subtle major grid at linewidth=0.2;
+          strip border (INK_SOFT) slightly heavy
+      - id: DE-03
+        name: Data Storytelling
+        score: 4
+        max: 6
+        passed: true
+        comment: Color coding of significant vs non-significant lags creates clear
+          visual hierarchy; AR(2) patterns (decaying ACF, PACF cutoff at lag 2) tell
+          a textbook-quality story
+    spec_compliance:
+      score: 15
+      max: 15
+      items:
+      - id: SC-01
+        name: Plot Type
+        score: 5
+        max: 5
+        passed: true
+        comment: ACF top + PACF bottom via facet_wrap; vertical stems from zero; shared
+          x-axis; dashed CI lines
+      - id: SC-02
+        name: Required Features
+        score: 4
+        max: 4
+        passed: true
+        comment: Lag 0 in ACF; PACF from lag 1; CI at ±1.96/sqrt(300); 36 lags (within
+          30-40 range)
+      - id: SC-03
+        name: Data Mapping
+        score: 3
+        max: 3
+        passed: true
+        comment: X=lag numbers, Y=correlation values; both panels correctly mapped
+      - id: SC-04
+        name: Title & Legend
+        score: 3
+        max: 3
+        passed: true
+        comment: Title 'acf-pacf · r · ggplot2 · anyplot.ai' matches required format;
+          no legend needed (guide='none' appropriate)
+    data_quality:
+      score: 15
+      max: 15
+      items:
+      - id: DQ-01
+        name: Feature Coverage
+        score: 6
+        max: 6
+        passed: true
+        comment: Shows ACF decay + PACF cutoff; significant and non-significant lags;
+          300 observations (within recommended range)
+      - id: DQ-02
+        name: Realistic Context
+        score: 5
+        max: 5
+        passed: true
+        comment: AR(2) synthetic series — standard time series example appropriate
+          for ACF/PACF demonstration
+      - id: DQ-03
+        name: Appropriate Scale
+        score: 4
+        max: 4
+        passed: true
+        comment: Correct AR(2) parameters; ACF lag 0=1.0; CI at ±1.96/sqrt(300)≈±0.113
+          — mathematically correct
+    code_quality:
+      score: 10
+      max: 10
+      items:
+      - id: CQ-01
+        name: KISS Structure
+        score: 3
+        max: 3
+        passed: true
+        comment: 'Clean linear structure: imports → tokens → data → plot → save'
+      - id: CQ-02
+        name: Reproducibility
+        score: 2
+        max: 2
+        passed: true
+        comment: set.seed(42) present
+      - id: CQ-03
+        name: Clean Imports
+        score: 2
+        max: 2
+        passed: true
+        comment: Only ggplot2 and ragg imported — both used
+      - id: CQ-04
+        name: Code Elegance
+        score: 2
+        max: 2
+        passed: true
+        comment: Idiomatic use of geom_segment + aes(color=significant); no fake functionality
+      - id: CQ-05
+        name: Output & API
+        score: 1
+        max: 1
+        passed: true
+        comment: Saves as plot-%s.png; uses linewidth (not deprecated size) for ggplot2
+          ≥3.4
+    library_mastery:
+      score: 8
+      max: 10
+      items:
+      - id: LM-01
+        name: Idiomatic Usage
+        score: 5
+        max: 5
+        passed: true
+        comment: 'Grammar-of-graphics approach: aesthetic mapping of significance
+          boolean to color; facet_wrap with free_y; proper theme layering'
+      - id: LM-02
+        name: Distinctive Features
+        score: 3
+        max: 5
+        passed: true
+        comment: Uses ggplot2-distinctive aesthetic mapping (aes(color=significant))
+          and faceting with scale independence — recognizable grammar approach, though
+          could go further
+  verdict: APPROVED
+impl_tags:
+  dependencies:
+  - ragg
+  techniques:
+  - faceting
+  - layer-composition
+  patterns:
+  - data-generation
+  dataprep:
+  - time-series
+  styling:
+  - grid-styling