highlightr

This package is designed to map a group of individuals’ notes to the corresponding parent text, based on the frequency with which phrases occur in the individual notes. The parent text is highlighted corresponding to this frequency, in order to create a ‘heatmap’ of popular phrases found in the note sheets.

This example is taken from the initial description of a crime used in a study of jury perception of algorithm use and demonstrative evidence.

The first step is to re-assign names in the notepad text to correspond with the expected format used in token_comments() and use the function to tokenize the comments.

library(highlightr)
comment_example_rename <- dplyr::rename(comment_example, page_notes=Notes)

toks_comment <- token_comments(comment_example_rename)

The next step is to tokenize the transcript in a similar manner.

transcript_example_rename <- dplyr::rename(transcript_example, text=Text)

toks_transcript <- token_transcript(transcript_example_rename)

After that, a fuzzy collocation is used to match the tokenized notes to the phrases in the tokenized transcript. This function first determines the number of times a collocation of length 5 occurs in participant notes. Fuzzy (or indirect) matches are then added to the frequency count of the transcript collocation that is the closest match. These fuzzy matches are weighted based on the edit distance between the transcript collocation and the indirect phrase: \[ \frac{n}{(d + 0.25)*m} \]

Here, \(n\) is the frequency of the fuzzy collocation, \(d\) is the distance between the fuzzy collocation and the transcript collocation, and \(m\) is the number of closest matches for the fuzzy collocation.

collocation_object <- collocate_comments_fuzzy(toks_transcript, toks_comment)

head(collocation_object)
#> # A tibble: 6 × 8
#>   word_number col_1 col_2 col_3 col_4 col_5 to_merge  collocation               
#>         <int> <dbl> <dbl> <dbl> <dbl> <dbl> <chr>     <chr>                     
#> 1           1  6.85 NA    NA    NA    NA    in        in this case the defendant
#> 2           2  7     6.85 NA    NA    NA    this      this case the defendant r…
#> 3           3  7.44  7     6.85 NA    NA    case      case the defendant richar…
#> 4           4 10.1   7.44  7     6.85 NA    the       the defendant richard col…
#> 5           5 11.4  10.1   7.44  7     6.85 defendant defendant richard cole ha…
#> 6           6 23.0  11.4  10.1   7.44  7    richard   richard cole has been cha…

The output assigns the frequency of each collocation to each word that occurs in that collocation. For example, the first collocation in the description is “in this case the defendant”, which occurs with a frequency of 6.85. This is the only collocation in which the first word will appear, so this is the only collocation value provided for the first word. The second word, “this” appears in the next collocation as well: this case the defendant richard, whose frequency is 7, and so on for all words in the description.

Next, the transcript_frequency() function attaches the collocation counts to the full text of the transcript. The collocation frequencies are averaged per word.

merged_frequency <- transcript_frequency(transcript_example_rename, collocation_object)

The combined document is then fed through ggplot to assign gradient colors based on frequency, and the minimum and maximum values are recorded.

freq_plot <- collocation_plot(merged_frequency)

After colors have been assigned, highlighted text is created based on frequency, as well as a gradient bar indicating the high and low values. The left side of each word gradient indicates the frequency of the previous word’s averaged collocation frequency, while the right side indicates the current word’s averaged collocation frequency.


page_highlight <- highlighted_text(freq_plot)
0
46
In 
this 
case, 
the 
defendant 
- 
Richard 
Cole 
- 
has 
been 
charged 
with 
willfully 
discharging 
a 
firearm 
in 
a 
place 
of 
business. 
This 
crime 
is 
a 
felony. 


Mr. 
Cole 
has 
pleaded 
not 
guilty 
to 
the 
charge. 


You 
will 
now 
read 
a 
summary 
of 
the 
case. 
This 
summary 
was 
prepared 
by 
an 
objective 
court 
clerk. 
It 
describes 
select 
evidence 
that 
was 
presented 
at 
trial. 


To exclude fuzzy matches, the collocate_comments() function can be used. Here, the listed frequencies are all whole numbers, because they are counts (without weighting).

collocation_object_nonfuzzy <- collocate_comments(toks_transcript, toks_comment)

head(collocation_object_nonfuzzy)
#> # A tibble: 6 × 8
#>   word_number col_1 col_2 col_3 col_4 col_5 to_merge  collocation               
#>         <int> <dbl> <dbl> <dbl> <dbl> <dbl> <chr>     <chr>                     
#> 1           1     6    NA    NA    NA    NA in        in this case the defendant
#> 2           2     7     6    NA    NA    NA this      this case the defendant r…
#> 3           3     7     7     6    NA    NA case      case the defendant richar…
#> 4           4    10     7     7     6    NA the       the defendant richard col…
#> 5           5    10    10     7     7     6 defendant defendant richard cole ha…
#> 6           6    21    10    10     7     7 richard   richard cole has been cha…

In this case, the highlighting pattern resembles that when the fuzzy matches are included, but the maximum value reached is smaller. Note also that the colors used in highlighting can be changed in the “colors” argument of the collocation_plot function.

merged_frequency_nonfuzzy <- transcript_frequency(transcript_example_rename, collocation_object_nonfuzzy)

freq_plot_nonfuzzy <- collocation_plot(merged_frequency_nonfuzzy, colors=c("#15bf7e", "#fcc7ed"))

page_highlight_nonfuzzy <- highlighted_text(freq_plot_nonfuzzy)
0
41
In 
this 
case, 
the 
defendant 
- 
Richard 
Cole 
- 
has 
been 
charged 
with 
willfully 
discharging 
a 
firearm 
in 
a 
place 
of 
business. 
This 
crime 
is 
a 
felony. 


Mr. 
Cole 
has 
pleaded 
not 
guilty 
to 
the 
charge. 


You 
will 
now 
read 
a 
summary 
of 
the 
case. 
This 
summary 
was 
prepared 
by 
an 
objective 
court 
clerk. 
It 
describes 
select 
evidence 
that 
was 
presented 
at 
trial. 


Additionally, the length of the collocation can be changed. The default collocation length (shown above) is 5 words. Below, this collocation length has been changed to 2 words.

collocation_object_2col <- collocate_comments(toks_transcript, toks_comment, collocate_length = 2)

head(collocation_object_2col, n=7)
#> # A tibble: 7 × 5
#>   word_number col_1 col_2 to_merge  collocation      
#>         <int> <dbl> <dbl> <chr>     <chr>            
#> 1           1   6      NA in        in this          
#> 2           2   7       6 this      this case        
#> 3           3   7       7 case      case the         
#> 4           4  10       7 the       the defendant    
#> 5           5  21      10 defendant defendant richard
#> 6           6  87      21 richard   richard cole     
#> 7           7  18.5    87 cole      cole has

In these shorter collocations, we can see that the collocation containing the name “Richard Cole” is popular, with a frequency of 87.

merged_frequency_2col <- transcript_frequency(transcript_example_rename, collocation_object_2col)

freq_plot_2col <- collocation_plot(merged_frequency_2col)

page_highlight_2col <- highlighted_text(freq_plot_2col)
0
72
In 
this 
case, 
the 
defendant 
- 
Richard 
Cole 
- 
has 
been 
charged 
with 
willfully 
discharging 
a 
firearm 
in 
a 
place 
of 
business. 
This 
crime 
is 
a 
felony. 


Mr. 
Cole 
has 
pleaded 
not 
guilty 
to 
the 
charge. 


You 
will 
now 
read 
a 
summary 
of 
the 
case. 
This 
summary 
was 
prepared 
by 
an 
objective 
court 
clerk. 
It 
describes 
select 
evidence 
that 
was 
presented 
at 
trial.