Last updated: 2020-09-03
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Knit directory: drift-workflow/analysis/
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suppressMessages({
library(flashier)
library(drift.alpha)
library(tidyverse)
})
I run some more experiments on the balanced tree with four populations of equal sizes to try to get a better understanding of what’s going on.
sim_tree <- function(n_range,
p = 10000,
branch_means,
branch_sds,
resid_sd = 0.1,
admix_pops = NULL,
outgroup = FALSE,
seed = 666) {
set.seed(666)
depth <- length(branch_means)
npop_pure <- 2^(depth - 1)
if (is.null(admix_pops)) {
admix_pops <- matrix(nrow = 0, ncol = 0)
}
npop_admix <- ncol(admix_pops)
npop <- npop_pure + npop_admix + outgroup
if (length(n_range) == 1) {
n <- rep(n_range, npop)
} else {
n <- sample(30:100, npop, replace = TRUE)
}
K <- 2^depth - 1
FF <- matrix(nrow = p, ncol = K)
k <- 1
for (d in 1:depth) {
for (i in 1:(2^(d - 1))) {
FF[, k] <- rnorm(p, sd = branch_means[d] + rnorm(1, sd = branch_sds[d]))
k <- k + 1
}
}
tree_mat <- matrix(0, nrow = npop_pure, ncol = K)
k <- 1
for (d in 1:depth) {
size <- 2^(depth - d)
for (i in 1:(2^(d - 1))) {
tree_mat[((i - 1) * size + 1):(i * size), k] <- 1
k <- k + 1
}
}
pop_means <- FF %*% t(tree_mat)
if (npop_admix > 0) {
pop_means <- cbind(pop_means, pop_means %*% admix_pops)
}
if (outgroup) {
pop_means <- cbind(pop_means, rnorm(p, mean = 0, sd = sqrt(sum(branch_sds^2))))
}
Y <- NULL
for (i in 1:npop) {
Y <- rbind(Y, matrix(pop_means[, i], nrow = n[i], ncol = p, byrow = TRUE))
}
Y <- Y + rnorm(sum(n) * p, sd = resid_sd)
plot_fl <- function(fl) {
dr <- init_from_flash(fl)
sd <- sqrt(dr$prior_s2)
L <- dr$EL
LDsqrt <- L %*% diag(sd)
K <- ncol(LDsqrt)
plot_loadings(LDsqrt[,1:K], rep(letters[1:npop], n)) +
scale_color_brewer(palette="Set3")
}
return(list(Y = Y, plot_fn = plot_fl))
}
init.mean.factor <- function(resids, zero.idx) {
u <- matrix(1, nrow = nrow(resids), ncol = 1)
u[zero.idx, 1] <- 0
v <- t(solve(crossprod(u), crossprod(u, resids)))
return(list(u, v))
}
balanced_4pop <- sim_tree(n_range = 50,
p = 10000,
branch_means = rep(1, 3),
branch_sds = rep(0, 3),
resid_sd = 0.1)
In an earlier analysis, I needed to do a backfit in order to find sparse third and fourth factors via rotation. Ideally, though, the greedy approach would be able to find a sparse third factor. But it doesn’t:
fl_pl <- flash.init(balanced_4pop$Y) %>%
flash.set.verbose(0) %>%
flash.add.greedy(Kmax = 3,
prior.family = c(prior.point.laplace(), prior.normal())) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 0)
balanced_4pop$plot_fn(fl_pl)
Version | Author | Date |
---|---|---|
f2b82dc | Jason Willwerscheid | 2020-09-03 |
This is not a convergence issue: if I initialize to a sparse factor (by, for example, keeping only the first three factors from the fit from the previous analysis), I get the same result:
fl_pl2 <- flash.init(balanced_4pop$Y) %>%
flash.set.verbose(0) %>%
flash.add.greedy(Kmax = 4,
prior.family = c(prior.point.laplace(), prior.normal())) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 0)
fl_pl3 <- fl_pl2 %>%
flash.remove.factors(kset = 4) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 0)
balanced_4pop$plot_fn(fl_pl3)
Version | Author | Date |
---|---|---|
f2b82dc | Jason Willwerscheid | 2020-09-03 |
What’s happening is that we’re getting the third principal component and there’s a sufficiently large gap between the third and fourth singular values for the non-sparse third PC to be preferred to a sparse linear combination of the third and fourth PCs.
svd_res <- svd(balanced_4pop$Y)
cat("First four singular values:", round(svd_res$d[1:4]))
#> First four singular values: 1877 1216 713 694
The third PC appears as follows:
plot(svd_res$u[, 3])
Version | Author | Date |
---|---|---|
f2b82dc | Jason Willwerscheid | 2020-09-03 |
This is not due to residual noise, but (I think) to the fact that the simulated branches aren’t exactly orthogonal. If I remove the noise altogether, I get the same result:
balanced_4pop_smallsd <- sim_tree(n_range = 50,
p = 10000,
branch_means = rep(1, 3),
branch_sds = rep(0, 3),
resid_sd = 0)
fl_pl4 <- flash.init(balanced_4pop_smallsd$Y) %>%
flash.set.verbose(0) %>%
flash.add.greedy(Kmax = 3,
prior.family = c(prior.point.laplace(), prior.normal())) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 0)
balanced_4pop$plot_fn(fl_pl4)
Version | Author | Date |
---|---|---|
f2b82dc | Jason Willwerscheid | 2020-09-03 |
If I force the prior to put some mass on the pointmass at zero (here, I fix the mixture proportions at c(0.5, 0.5)
), I again get the same result:
g <- ebnm::laplacemix(pi = c(0.5, 0.5), mean = c(0, 0), scale = c(0, 1))
fl_pl5 <- flash.init(balanced_4pop$Y) %>%
flash.set.verbose(0) %>%
flash.add.greedy(Kmax = 3,
prior.family = c(prior.point.laplace(g_init = g, fix_g = TRUE),
prior.normal())) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 0)
balanced_4pop$plot_fn(fl_pl5)
Version | Author | Date |
---|---|---|
f2b82dc | Jason Willwerscheid | 2020-09-03 |
The result is the same if I use a sparse initialization. I show the initialization and details for 25 iterations, which is sufficient to get to a non-sparse solution:
fl_pl6 <- flash.init(balanced_4pop$Y) %>%
flash.set.verbose(0) %>%
flash.add.greedy(Kmax = 4,
prior.family = c(prior.point.laplace(g_init = g, fix_g = TRUE),
prior.normal())) %>%
flash.backfit(tol = 1e-3, verbose.lvl = 0) %>%
flash.remove.factors(kset = 4)
balanced_4pop$plot_fn(fl_pl6)
verbose.fns <- c(flashier:::calc.obj.diff,
function(new, old, k) {
round(sum(flashier:::get.KL(new, n = 1)))
},
function(new, old, k) {
round(sum(flashier:::get.KL(new, n = 2)))
},
function(new, old, k) {
round(flashier:::get.obj(new) -
sum(flashier:::get.KL(new, n = 1)) -
sum(flashier:::get.KL(new, n = 2)))
})
verbose.colnames <- c("ELBO diff", "KL-div (L)", "KL-div (F)", "fit (llik)")
verbose.colwidths <- c(12, 14, 14, 14)
fl_pl7 <- fl_pl6 %>%
flash.set.verbose(3, verbose.fns, verbose.colnames, verbose.colwidths) %>%
flash.backfit(tol = 1e-4, verbose.lvl = 3, maxiter = 25)
#> Backfitting 3 factors (tolerance: 1.00e-04)...
#> Iteration Factor ELBO diff KL-div (L) KL-div (F) fit (llik)
#> 1 all 3.48e+04 -3273 -94552 -1476575
#> 2 all 4.28e+02 -3542 -94231 -1476199
#> 3 all 9.53e+02 -3592 -94354 -1475073
#> 4 all 1.11e+03 -3598 -94385 -1473930
#> 5 all 1.20e+03 -3605 -94411 -1472694
#> 6 all 1.26e+03 -3613 -94441 -1471393
#> 7 all 1.21e+03 -3623 -94471 -1470144
#> 8 all 6.68e+02 -3635 -94497 -1469439
#> 9 all 2.24e-02 -3634 -94480 -1469457
#> 10 all 1.76e-02 -3634 -94479 -1469457
#> 11 all 2.35e-02 -3634 -94480 -1469457
#> 12 all 2.92e-02 -3634 -94480 -1469457
#> 13 all 3.16e-02 -3634 -94480 -1469457
#> 14 all 9.80e-03 -3634 -94480 -1469457
#> 15 all 2.96e-03 -3634 -94480 -1469457
#> 16 all 5.46e-03 -3634 -94480 -1469457
#> 17 all 8.18e-03 -3634 -94480 -1469457
#> 18 all 1.17e-02 -3634 -94480 -1469457
#> 19 all 1.61e-02 -3634 -94480 -1469457
#> 20 all 1.41e-02 -3634 -94480 -1469457
#> 21 all 2.19e-03 -3634 -94480 -1469457
#> 22 all 4.07e-03 -3634 -94480 -1469457
#> 23 all 6.16e-03 -3634 -94480 -1469457
#> 24 all 8.97e-03 -3634 -94480 -1469457
#> 25 all 1.27e-02 -3634 -94480 -1469457
#> --Maximum number of iterations reached!
#> Backfit complete. Objective: -1567570.423
#> Wrapping up...
#> Done.
balanced_4pop$plot_fn(fl_pl7)
There doesn’t appear to be a good way to get a sparse third factor using a greedy approach. Backfitting might be necessary.
sessionInfo()
#> R version 3.5.3 (2019-03-11)
#> Platform: x86_64-apple-darwin15.6.0 (64-bit)
#> Running under: macOS Mojave 10.14.6
#>
#> Matrix products: default
#> BLAS: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRblas.0.dylib
#> LAPACK: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRlapack.dylib
#>
#> locale:
#> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
#>
#> attached base packages:
#> [1] stats graphics grDevices utils datasets methods base
#>
#> other attached packages:
#> [1] forcats_0.4.0 stringr_1.4.0 dplyr_0.8.0.1
#> [4] purrr_0.3.2 readr_1.3.1 tidyr_0.8.3
#> [7] tibble_2.1.1 ggplot2_3.2.0 tidyverse_1.2.1
#> [10] drift.alpha_0.0.10 flashier_0.2.7
#>
#> loaded via a namespace (and not attached):
#> [1] Rcpp_1.0.4.6 lubridate_1.7.4 invgamma_1.1
#> [4] lattice_0.20-38 assertthat_0.2.1 rprojroot_1.3-2
#> [7] digest_0.6.18 truncnorm_1.0-8 R6_2.4.0
#> [10] cellranger_1.1.0 plyr_1.8.4 backports_1.1.3
#> [13] evaluate_0.13 httr_1.4.0 pillar_1.3.1
#> [16] rlang_0.4.2 lazyeval_0.2.2 readxl_1.3.1
#> [19] rstudioapi_0.10 ebnm_0.1-21 irlba_2.3.3
#> [22] whisker_0.3-2 Matrix_1.2-15 rmarkdown_1.12
#> [25] labeling_0.3 munsell_0.5.0 mixsqp_0.3-40
#> [28] broom_0.5.1 compiler_3.5.3 modelr_0.1.5
#> [31] xfun_0.6 pkgconfig_2.0.2 SQUAREM_2017.10-1
#> [34] htmltools_0.3.6 tidyselect_0.2.5 workflowr_1.2.0
#> [37] withr_2.1.2 crayon_1.3.4 grid_3.5.3
#> [40] nlme_3.1-137 jsonlite_1.6 gtable_0.3.0
#> [43] git2r_0.25.2 magrittr_1.5 scales_1.0.0
#> [46] cli_1.1.0 stringi_1.4.3 reshape2_1.4.3
#> [49] fs_1.2.7 xml2_1.2.0 generics_0.0.2
#> [52] RColorBrewer_1.1-2 tools_3.5.3 glue_1.3.1
#> [55] hms_0.4.2 parallel_3.5.3 yaml_2.2.0
#> [58] colorspace_1.4-1 ashr_2.2-51 rvest_0.3.4
#> [61] knitr_1.22 haven_2.1.1