Error in k-means and PCA when one time index is specified

[markromanmiller]

I'm trying to calculate k-means and PCA from a distribution of rotation data without time series information. However, what I expected would work (constructing a qts_sample series where each sample is one point long, and specifying no time-warping for kmeans) instead led to errors. Is there some other approach I should take, or am I misunderstanding what is necessary to complete k-means/PCA/distance matrix in rotation space?

If helpful, here's a reprex:

library(squat)
# works
working_sample <- as_qts_sample(lapply(vespa64$igp[1:20], function(m) {m[1:10,]}))
kmeans(working_sample, 2, warping_class="none")

# does not work
failing_sample <- as_qts_sample(lapply(vespa64$igp[1:20], function(m) {m[1,]}))
kmeans(failing_sample, 2, warping_class="none")

R version 4.3.1 (2023-06-16)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 23.10

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.11.0 
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.11.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

time zone: America/Chicago
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] squat_0.3.0

loaded via a namespace (and not attached):
 [1] utf8_1.2.4        generics_0.1.3    tidyr_1.3.0       stringi_1.8.2     digest_0.6.33     magrittr_2.0.3   
 [7] grid_4.3.1        evaluate_0.23     timechange_0.2.0  pkgload_1.3.3     fastmap_1.1.1     processx_3.8.2   
[13] pkgbuild_1.4.2    sessioninfo_1.2.2 urlchecker_1.0.1  ps_1.7.5          promises_1.2.1    purrr_1.0.2      
[19] fansi_1.0.6       scales_1.3.0      cli_3.6.2         shiny_1.8.0       rlang_1.1.3       crayon_1.5.2     
[25] munsell_0.5.0     ellipsis_0.3.2    yaml_2.3.7        remotes_2.4.2.1   cachem_1.0.8      devtools_2.4.5   
[31] tools_4.3.1       memoise_2.0.1     dplyr_1.1.4       colorspace_2.1-0  ggplot2_3.5.0     httpuv_1.6.12    
[37] vctrs_0.6.5       R6_2.5.1          mime_0.12         lifecycle_1.0.4   lubridate_1.9.3   stringr_1.5.1    
[43] fs_1.6.3          htmlwidgets_1.6.3 usethis_2.2.2     miniUI_0.1.1.1    pkgconfig_2.0.3   callr_3.7.3      
[49] gtable_0.3.4      pillar_1.9.0      later_1.3.1       glue_1.7.0        profvis_0.3.8     Rcpp_1.0.11      
[55] xfun_0.41         tibble_3.2.1      tidyselect_1.2.0  knitr_1.45        rstudioapi_0.15.0 xtable_1.8-4     
[61] htmltools_0.5.7   rmarkdown_2.25    compiler_4.3.1    prettyunits_1.2.0

Thanks!