Align signatures

Align all signatures in the same group. All signatures in this group are aligned with respect to the first signature in a group. Alignments will vary depending on which signature is used as 'first'. TODO: check on resolution IMPORTANT: the value vectors have to be in the same order for each group and taken on the same, equi-distant grid (no missing values!)

Usage

sig_align_set(data, value, group, min.overlap = 500)

Arguments

data

data frame with id, signatures and grouping variable

value

symbol for the signature values

group

symbol (variable) for grouping

min.overlap

value passed on to get_ccf, see bulletxtrctr::get_ccf.

Value

data frame: the returned data frame has the same number of observations as the input, but has the additional variables aligned_x and ccf. Note that aligned_x is reported in integer values. For a conversion to the physical extent, scale by the resolution of the scan.

Examples

library(dplyr)
#> 
#> Attaching package: ‘dplyr’
#> The following objects are masked from ‘package:stats’:
#> 
#>     filter, lag
#> The following objects are masked from ‘package:base’:
#> 
#>     intersect, setdiff, setequal, union
data(toolmarks)
names(toolmarks)
#>  [1] "tool"      "size"      "side"      "direction" "angle"     "mark"     
#>  [7] "TID"       "x"         "y"         "value"     "signature"
tool2AL <- dplyr::filter(toolmarks, tool == 2, side=="A", size=="L")
# Align all signatures in one go
aligned <- tool2AL %>% mutate(mark_angle = interaction(mark, angle)) %>%
  sig_align_set(value = signature,  group = mark_angle, min.overlap = 500)

# Visualize the results:
library(ggplot2)
aligned %>%
  ggplot(aes(x = aligned_x, y = signature, colour = mark_angle)) +
  geom_line()

# HH: mark 4.60 is still travelling in reversed direction

wide <- aligned %>% select(aligned_x, signature, mark_angle) %>%
   tidyr::pivot_wider(values_from = signature, names_from = mark_angle)
heatmap(cor(wide %>% select(-aligned_x), use="pairwise.complete"))


# Align signatures separately by angle
long <- tool2AL %>% group_by(angle) %>% tidyr::nest()
long <- long %>%  mutate(
  data = data %>% purrr::map(.f = function(d) {
    d %>% sig_align_set(value = signature,  group = mark, min.overlap=500)
  })
)
long$data[[3]] %>% ggplot(aes(x = aligned_x, y = signature, colour = factor(mark))) + geom_line()


long <- long %>% tidyr::unnest(col=data)
long %>%
  ggplot(aes(x =aligned_x, y = signature, colour = factor(mark))) +
  geom_line() +
  facet_grid(angle~., labeller="label_both")