Last updated: 2020-05-18

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Introduction

  • I apply ebpmf.alpha (version 0.3.9) to KOS dataset. I use \(K = 50\). The data has \(n = 3430,p = 6906\) and sparsity around \(98\) percent.
  • Besides, I also apply to PMF (lee’s, but I implemented a version for sparse data) to the same dataset with the same initialization. In each iteration, ebpmf_bg does two things: MLE for prior and updates posterior. The second part has almost the same computation as in PMF.

model

\[\begin{align} & X_{ij} = \sum_k Z_{ijk}\\ & Z_{ijk} \sim Pois(l_{i0} f_{j0} l_{ik} f_{jk})\\ & l_{ik} \sim g_{L, k}(.), f_{jk} \sim g_{F, k}(.) \end{align}\]

For details see ebpmf_bg

prior options

I use gamma mixture \(\sum_l \pi_{l} Ga(1/\phi_l, 1/\phi_l)\) as prior for both \(L, F\). Note that each grid component has \(E = 1, Var = \phi_L\)

initialization

I initialized with 50 runs of NNLM::nnmf (scd). Then I used medians of each row of \(L, F\) as \(l_{i0}, f_{j0}\), and \(l_{ik} = l^0_{ik}/l_{i0}, f_{jk} = f^0_{jk}/f_{j0}\).

library(pheatmap)
Warning: package 'pheatmap' was built under R version 3.5.2
library(gridExtra)
source("code/misc.R")
source("code/util.R")

output_dir = "output/uci_BoW/v0.3.9/"
data_dir = "data/uci_BoW/"
model_name = "kos_ebpmf_bg_initLF50_K50_maxiter2000.Rds"
model_pmf_name = "kos_pmf_initLF50_K50_maxiter2000.Rds"
dict_name = "vocab.kos.txt"
data_name = "docword.kos.txt"

Y = read_uci_bag_of_words(file= sprintf("%s/%s",
                data_dir,data_name))
model = readRDS(sprintf("%s/%s", output_dir, model_name))
model_pmf = readRDS(sprintf("%s/%s", output_dir, model_pmf_name))
dict = read.csv(sprintf("%s/%s", data_dir, dict_name), header = FALSE)[,1]
dict = as.vector(dict)

K = ncol(model_pmf$L)
L_pmf = model_pmf$L; F_pmf = model_pmf$F
L_bg = model$l0 * model$qg$qls_mean; F_bg = model$f0 * model$qg$qfs_mean
lf = poisson2multinom(L=L_bg,F=F_bg)
lf_pmf = poisson2multinom(L = L_pmf,F = F_pmf)

ELBO and runtime

plot(model$ELBO, xlab = "niter", ylab = "elbo")

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## see when it "converges"
plot(model$ELBO[1:200], xlab = "niter", ylab = "elbo")

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## ebpmf_bg runtime per iteration
model$runtime/length(model$ELBO)
      user     system    elapsed 
25.1001780  0.0507705 25.1611020 
## pmf runtime per iteration
model_pmf$runtime/length(model_pmf$log_liks)
     user    system   elapsed 
11.738463  0.042293 11.784945 

look at priors in ebpmf_bg

\(g_L\)

get_prior_summary(model$qg$gls)

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\(g_F\)

get_prior_summary(model$qg$gfs)

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look at \(s_k\) (ebpmf_bg)

\(s_k := \sum_i l_i0 \bar{l}_{ik}\). I make \(\sum_j f_{j0} = 1\) for interpretability.

d = sum(model$f0)
s_k = colSums(d * model$l0 * model$qg$qls_mean)
names(s_k) <- paste("Topic", 1:K, sep = "")
step = 5
for(i in 1:round(K/step)){
  print(round(s_k[((i-1)*step + 1):(i*step)]))
}
Topic1 Topic2 Topic3 Topic4 Topic5 
  7544   7216   7912  25180  35652 
 Topic6  Topic7  Topic8  Topic9 Topic10 
   6709   21141    7208   11120   15791 
Topic11 Topic12 Topic13 Topic14 Topic15 
   6953   12764    6206   25344   11313 
Topic16 Topic17 Topic18 Topic19 Topic20 
  21599   13245   25545   25615   17418 
Topic21 Topic22 Topic23 Topic24 Topic25 
  25117   24237   17946   22377   11739 
Topic26 Topic27 Topic28 Topic29 Topic30 
  12942   20370    5179   13057   15220 
Topic31 Topic32 Topic33 Topic34 Topic35 
  19897   22743   18122   17739   14611 
Topic36 Topic37 Topic38 Topic39 Topic40 
  14671   30433   15525   16151   11059 
Topic41 Topic42 Topic43 Topic44 Topic45 
  18014   11715   19915   12562   15720 
Topic46 Topic47 Topic48 Topic49 Topic50 
  22557   23555   13324   18395   20023 

what does background capture

compared to rank-1 fit

Is the background very different from the rank-1 model? The rank-1 MLE has \(l_{i0} \propto \sum_j X_{ij}\) and \(f_{j0} \propto \sum_i X_{ij}\). Let’s see if the fitted background model is close to it.

Y_cs = Matrix::colSums(Y)
Y_cs_scaled = Y_cs/sum(Y_cs)
f0_scaled = model$f0/sum(model$f0)
plot(f0_scaled, Y_cs_scaled)

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7928026 zihao12 2020-05-16
Y_rs = Matrix::rowSums(Y)
Y_rs_scaled = Y_rs/sum(Y_rs)
l0_scaled = model$l0/sum(model$l0)
plot(l0_scaled, Y_rs_scaled)

compared to median/mean of PMF fit

The median of \(L\) from PMF are all 0, so I use mean instead for it

f0_pmf = apply(F_pmf, 1, median)
f0_pmf_scaled = f0_pmf/sum(f0_pmf)

l0_pmf = apply(L_pmf, 1, mean)
l0_pmf_scaled = l0_pmf/sum(l0_pmf)

plot(f0_scaled, f0_pmf_scaled)

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plot(l0_scaled, l0_pmf_scaled)

Compare \(L, F\) (in the context of PMF model)

See plots.
Note: I scale them as below

## scale L, F so that colSums(F) = 1
L_pmf = L_pmf %*% diag(colSums(F_pmf))
F_pmf = F_pmf %*% diag(1/colSums(F_pmf))

L_bg = L_bg %*% diag(colSums(F_bg))
F_bg = F_bg %*% diag(1/colSums(F_bg))

look at top words for topics

See plots.
Note: for each topic:
* the first row selects the top words from \(\bar{f}_{Jk}\), and show them in \(\bar{f}\)(bg) and \(f\) (PMF) respectively.
* The second row shows the top words from \(f_{J0}0\bar{f}_{Jk}\) (bg) and \(f_{Jk}\) (PMF)
* The third row transforms \(f_{J0}0\bar{f}_{Jk}\) (bg) and \(f_{Jk}\) into multinomial model and show their top words.

take a closer look at some top words

I pick two top words from \(\bar{f}_{J1}\) and two top words from \(f_{J1}\):

d = Matrix::summary(Y)
## `burt`
idx = which(dict == "burt")
### number of occurence
sum(d$j == idx)
[1] 16
table(Y[,idx])

   0    1    2    6 
3414   13    2    1 
### background value
model$f0[idx]
[1] 1.482282e-05
## `knowles`
idx = which(dict == "knowles")
### number of occurence
sum(d$j == idx)
[1] 78
table(Y[,idx])

   0    1    2    3    4    5    6    7    8    9   12 
3352   42   12    5    6    3    2    3    2    1    2 
### background value
model$f0[idx]
[1] 4.240542e-05
## `campaign`
idx = which(dict == "campaign")
### number of occurence
sum(d$j == idx)
[1] 960
table(Y[,idx])

   0    1    2    3    4    5    6    7    8    9   10   11   12   16 
2470  511  204  104   58   36   20   11    7    4    1    2    1    1 
### background value
model$f0[idx]
[1] 0.001817356
## `people`
idx = which(dict == "people")
### number of occurence
sum(d$j == idx)
[1] 989
table(Y[,idx])

   0    1    2    3    4    5    6    7    8   13 
2441  632  199   91   35   13    9    3    5    2 
### background value
model$f0[idx]
[1] 0.001846341

sessionInfo()
R version 3.5.1 (2018-07-02)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS  10.14

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] gridExtra_2.3   pheatmap_1.0.12

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.2         knitr_1.28         whisker_0.3-2      magrittr_1.5      
 [5] workflowr_1.6.2    munsell_0.5.0      lattice_0.20-38    colorspace_1.4-1  
 [9] R6_2.4.0           stringr_1.4.0      tools_3.5.1        grid_3.5.1        
[13] gtable_0.3.0       xfun_0.8           git2r_0.26.1       htmltools_0.3.6   
[17] yaml_2.2.0         digest_0.6.22      rprojroot_1.3-2    Matrix_1.2-17     
[21] RColorBrewer_1.1-2 later_0.8.0        promises_1.0.1     fs_1.3.1          
[25] glue_1.3.1         evaluate_0.14      rmarkdown_2.1      stringi_1.4.3     
[29] compiler_3.5.1     scales_1.0.0       backports_1.1.5    httpuv_1.5.1