Running examples in 'cytominer-Ex.R' failed
The error most likely occurred in:

> ### Name: correlation_threshold
> ### Title: Remove redundant variables.
> ### Aliases: correlation_threshold
> 
> ### ** Examples
> 
> 
> suppressMessages(suppressWarnings(library(magrittr)))
> sample <- tibble::data_frame(
+    x = rnorm(30),
+    y = rnorm(30)/1000
+  )
>  
> sample %<>% dplyr::mutate(z = x + rnorm(30) / 10)
> variables <- c("x", "y", "z")
> 
> head(sample)
# A tibble: 6 x 3
       x          y      z
   <dbl>      <dbl>  <dbl>
1 -0.626  0.00136   -0.386
2  0.184 -0.000103   0.180
3 -0.836  0.000388  -0.767
4  1.60  -0.0000538  1.60 
5  0.330 -0.00138    0.255
6 -0.820 -0.000415  -0.802
> cor(sample)
           x          y          z
x 1.00000000 0.04866964 0.99466179
y 0.04866964 1.00000000 0.09519371
z 0.99466179 0.09519371 1.00000000
> 
> # `x` and `z` are highly correlated; one of them will be removed
> 
> correlation_threshold(variables, sample)
Error in namespaceExport(ns, exports) : 
  undefined exports: %s!=%, %s!==%, %s+%, %s<%, %s<=%, %s==%, %s===%, %s>%, %s>=%, %stri!=%, %stri!==%, %stri+%, %stri<%, %stri<=%, %stri==%, %stri===%, %stri>%, %stri>=%, stri_datetime_add<-, stri_sub<-, stri_subset<-, stri_subset_charclass<-, stri_subset_coll<-, stri_subset_fixed<-, stri_subset_regex<-, stri_c, stri_c_list, stri_cmp, stri_cmp_eq, stri_cmp_equiv, stri_cmp_ge, stri_cmp_gt, stri_cmp_le, stri_cmp_lt, stri_cmp_neq, stri_cmp_nequiv, stri_compare, stri_conv, stri_count, stri_count_boundaries, stri_count_charclass, stri_count_coll, stri_count_fixed, stri_count_regex, stri_count_words, stri_datetime_add, stri_datetime_create, stri_datetime_fields, stri_datetime_format, stri_datetime_fstr, stri_datetime_now, stri_datetime_parse, stri_datetime_symbols, stri_detect, stri_detect_charclass, stri_detect_coll, stri_detect_fixed, stri_detect_regex, stri_dup, stri_duplicated, stri_duplicated_any, stri_enc_detect, stri_enc_detect2, stri_enc_fromutf32, stri_enc_get, stri_enc_inf
Calls: correlation_threshold ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
Execution halted