Add matchStart and matchEnd columns to collectedMatches in corpusQuery result

Resolves #22

Change-Id: I6af9de503e5911cbe5c566b0fae529cfba7b764c
diff --git a/demo/relativeTextpositionBoxplot.R b/demo/relativeTextpositionBoxplot.R
new file mode 100644
index 0000000..02823da
--- /dev/null
+++ b/demo/relativeTextpositionBoxplot.R
@@ -0,0 +1,57 @@
+library(RKorAPClient)
+library(highcharter)
+library(tidyverse)
+
+kco <- new("KorAPConnection", verbose = TRUE)
+
+set.seed(7)
+
+get_relative_positions_sample <- function(kco, query, sampleSize = 400) {
+  res <- corpusQuery(kco, query)
+  res <- fetchNext(res, maxFetch = sampleSize, randomizePageOrder = TRUE)
+  matches <- res@collectedMatches
+  matches <- matches %>%
+    mutate(
+      query = query,
+      vc = paste0('textSigle="', textSigle, '"'),
+      textSize = corpusStats(kco, vc, as.df = TRUE)$tokens,
+      relativeTextPosition = matchStart / textSize
+    )
+  cat("\n\n", query, ":\n")
+  print(summary(matches$relativeTextPosition))
+  cat("\n\n")
+  return(matches)
+}
+
+df <- c(
+  "anfangs/i",
+  "zuguterletzt/i",
+  "zun\u00e4chst/i", # it is still necessary to encode non ascii characters in R package demos
+  "zuerst/i",
+  "zuletzt/i",
+  "schlie\u00dflich/i"
+) %>%
+  map(~ get_relative_positions_sample(kco, .)) %>%
+  bind_rows()
+
+hc_data <- df %>%
+  group_by(query) %>%
+  summarise(
+    min = min(relativeTextPosition),
+    q1 = quantile(relativeTextPosition, 0.25),
+    median = median(relativeTextPosition),
+    q3 = quantile(relativeTextPosition, 0.75),
+    max = max(relativeTextPosition)
+  ) %>%
+  mutate(data = pmap(list(min, q1, median, q3, max), c)) %>%
+  select(query, data)
+
+hc <- highchart() %>%
+  hc_chart(type = "boxplot", inverted = TRUE) %>%
+  hc_xAxis(categories = hc_data$query) %>%
+  hc_yAxis(ceiling = 1, title = list(text = "Relative position in text")) %>%
+  hc_add_series(data = hc_data$data) %>%
+  hc_title(text = "Relative positions of some adverbs in DeReKo texts") %>%
+  hc_legend(enabled = FALSE)
+
+print(hc)