Fix issue with missing control limits for length-1 display periods.

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: autospc
 Title: Automatically Partitioned SPC Charts
-Version: 0.0.0.9041
+Version: 0.0.0.9044
 Authors@R: c(
     person("Thomas", "Woodcock", , "woodcock.thomas@gmail.com", role = c("aut", "cre"),
            comment = c(ORCID = "0000-0002-4735-4856")),

R/visualisation.R

@@ -40,6 +40,8 @@ create_spc_plot <- function(df,
                   value,
                   everything())
 
+  df_long <- add_limit_connectors(df_long)
+
   # Create initial plot object without formatting
   pct <- ggplot2::ggplot(df_long %>%
                            dplyr::filter(!is.na(value)),
@@ -345,3 +347,53 @@ format_x_axis <- function(p,
   return(p)
 
 }
+
+
+add_limit_connectors <- function(df_long) {
+
+  x_sequence <- df_long %>%
+    dplyr::distinct(x) %>%
+    dplyr::arrange(x) %>%
+    dplyr::pull(x)
+
+  # Dataframe listing each display period in the data, with information on
+  # first x value in period, and previous x value to that, along with series
+  # values for that previous point
+  display_periods <- df_long %>%
+    dplyr::filter(periodType == "display") %>%
+    dplyr::distinct(plotPeriod,
+                    x) %>%
+    dplyr::group_by(plotPeriod) %>%
+    dplyr::summarise(x = dplyr::first(x)) %>%
+    dplyr::rowwise() %>%
+    dplyr::mutate(prev_x = x_sequence[which(x_sequence == x) - 1L]) %>%
+    dplyr::ungroup() %>%
+    dplyr::left_join(df_long %>%
+                       dplyr::distinct(x, series, value) %>%
+                       dplyr::rename(prev_value = value),
+                     by = c("prev_x" = "x")) 
+
+  # Create additional rows to be added into df_long with series values at the 
+  # point immediately before the start of each display period. This has the
+  # effect of creating an additional point for the control limits and centre
+  # line to connect with the preceding calculation period limits and centre line
+  display_starts <- df_long %>%
+    dplyr::inner_join(display_periods %>%
+                        dplyr::select(-plotPeriod),
+                      by = c("x" = "x",
+                             "series" = "series")) %>%
+    dplyr::filter(series %in% c("cl", "ucl", "lcl")) %>%
+    dplyr::mutate(x = prev_x,
+                  value = prev_value) %>%
+    dplyr::select(-prev_x,
+                  -prev_value)
+
+  # Add the extra rows into the data, and sort into x order
+  df_long <- df_long %>% 
+    dplyr::bind_rows(display_starts) %>%
+    dplyr::arrange(x,
+                   series)
+
+  return(df_long)
+
+}

tests/testthat/test_linetypes.R

@@ -6,22 +6,25 @@ test_that("Linetypes are formed correctly", {
                       chart_type = "C'")
 
   # layer 1 holds the centre line and control limits
-  layer_1 <- ggplot2::layer_data(test_plt, 1) %>% dplyr::arrange(x)
+  layer_1 <- ggplot2::layer_data(test_plt, 1) %>%
+    dplyr::arrange(x)
   # layer 2 holds the data series
-  layer_2 <- ggplot2::layer_data(test_plt, 2) %>% dplyr::arrange(x)
+  layer_2 <- ggplot2::layer_data(test_plt, 2) %>%
+    dplyr::arrange(x)
 
-  # layer 1 has 3n rows, as it holds three series
-  expect_equal(nrow(layer_1), 450L)
+  # layer 1 has 3n rows, as it holds three series; then an additional 3*3 = 9
+  # rows for the additional limit connectors added for continuity of limit lines
+  expect_equal(nrow(layer_1), 450L + 9L)
   # layer 2 has n rows, as it holds one series
   expect_equal(nrow(layer_2), 150L)
 
   rle_layer_1 <- rle(layer_1$linetype)
   rle_layer_2 <- rle(layer_2$linetype)
 
   correct_answer_1 <- structure(list(lengths = rep(c(1L, 2L),
-                                                   150),
+                                                   153),
                                      values = rep(c("solid", "42"),
-                                                  150)),
+                                                  153)),
                                 class = "rle")
   correct_answer_2 <- structure(list(lengths = 150L,
                                      values = "solid"),