Last updated: 2020-05-18

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Introduction

  • I apply ebpmf.alpha (version 0.3.9) to KOS dataset. I use \(K = 20\). 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_K20_maxiter2000.Rds"
model_pmf_name = "kos_pmf_initLF50_K20_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 
9.8637280 0.0321605 9.8995435 
## pmf runtime per iteration
model_pmf$runtime/length(model_pmf$log_liks)
     user    system   elapsed 
5.0050735 0.0110125 5.0175635 

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 
  6454  31772  19371  47805  26320 
 Topic6  Topic7  Topic8  Topic9 Topic10 
  23245   19511   19665   21904   23617 
Topic11 Topic12 Topic13 Topic14 Topic15 
  36115    7711   31393   33036   41066 
Topic16 Topic17 Topic18 Topic19 Topic20 
  23052   31233   24933   41539   30687 

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)

Version Author Date
88cc049 zihao12 2020-05-16
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 of PMF fit

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

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

plot(f0_scaled, f0_pmf_scaled)

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7928026 zihao12 2020-05-16
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

In topic 1, the word upenn seamus are the top words in \(\bar{f}_{J1}\), and november, bush are the top words in \(f_{J0}\bar{f}_{J1}\). Let’s see their correspoding \(f_{j0}\)

d = Matrix::summary(Y)
## `upenn`
idx = which(dict == "upenn")
### number of occurence
sum(d$j == idx)
[1] 76
table(Y[,idx])

   0    1 
3354   76 
### background value
model$f0[idx]
[1] 9.357511e-05
## `seamus`
idx = which(dict == "seamus")
### number of occurence
sum(d$j == idx)
[1] 58
table(Y[,idx])

   0    1 
3372   58 
### background value
model$f0[idx]
[1] 7.286948e-05
## `november`
idx = which(dict == "november")
### number of occurence
sum(d$j == idx)
[1] 630
table(Y[,idx])

   0    1    2    3   10   11   12   13 
2800  253   42    4  218  106    5    2 
### background value
model$f0[idx]
[1] 0.003117474
## `bush`
idx = which(dict == "bush")
### number of occurence
sum(d$j == idx)
[1] 2123
table(Y[,idx])

   0    1    2    3    4    5    6    7    8    9   10   11   12   13   14   15 
1307  743  469  275  175  127   75   82   43   39   32   18   14    8    4    4 
  16   17   18   19   22   24   25   27   29   34 
   4    1    3    1    1    1    1    1    1    1 
### background value
model$f0[idx]
[1] 0.004354958

“similar topics”

By looking at top words, I find topic 1 & 12 have some similarities. (danielua and misterajc are both names of authors)

f1 = model$qg$qfs_mean[, 1]
f2 = model$qg$qfs_mean[,12]
plot(f1, f2)

## those important in topic 1 but not so in topic 12
## note there are many key words in topic 1!
idx = which(f1 > 200 & f2 < 1)
dict[idx]
 [1] "abstain"         "anecdotal"       "bald"            "bradnickel"     
 [5] "buh"             "cfr"             "christopher"     "converted"      
 [9] "danielua"        "egon"            "furiousxgeorge"  "jiacinto"       
[13] "lawnorder"       "luaptifer"       "lud"             "maximumken"     
[17] "mom"             "nprigo"          "peanut"          "rad"            
[21] "seamus"          "senategovernors" "suppression"     "upenn"          
## those important in topic 12 but not so in topic 1
idx = which(f1 < 1 & f2 > 200)
dict[idx]
 [1] "allegory"         "barbero"          "bloomfield"       "chedrcheez"      
 [5] "countdown"        "crooks"           "gatana"           "hoodies"         
 [9] "hotshotxi"        "idetestthispres"  "juppon"           "katerina"        
[13] "kingelection"     "mich"             "misterajc"        "punkmonk"        
[17] "releasing"        "sappy"            "tradesports"      "vaantirepublican"
[21] "virginiadem"      "wclathe"         
## those important in both topics
idx = which(f1 > 100 & f2 > 100)
dict[idx]
 [1] "account"        "blast"          "challenging"    "function"      
 [5] "governor"       "homepage"       "locations"      "menu"          
 [9] "midday"         "november"       "ourcongressorg" "philly"        

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