Last updated: 2020-02-28

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Rmd 327dcd2 Dongyue Xie 2020-02-28 wflow_publish(“analysis/scdePBMC2.Rmd”)

Introduction

In my previous analysis, I tried RUV methods on single-cell RNA-Seq data. I only tried top 1000 expressed genes from the dataset. So only a few of gene expressions are 0. This is not what typically scRNA-Seq data are. Also, I tried only 50 cells.

This time, I’m going to try PBMC data prepared by Satjia Lab.

library(MAST)
library(Seurat)
datax = readRDS('data/pbmc_counts.rds')@assays$RNA
datax = datax[rowSums(datax)>0,]
clusters = readRDS('data/pbmc.rds')

cell_cluster = clusters@colData$seurat

How many zeros are there? A lot

sum(datax==0)/(dim(datax)[1]*dim(datax)[2])
[1] 0.9381137

Let’s only use the Naive CD4+ T cells, which corresponds to the first cluster. Total 709 cells.

CDT_idx = which(cell_cluster == 1)
CDT = datax[,CDT_idx]

set.seed(12345)
group1_idx = sample(1:ncol(CDT),ncol(CDT)/2)
group1 = CDT[,group1_idx]
group2 = CDT[,-group1_idx]
## for each gene, run a two-sample t test

p_values1 = c()
for(i in 1:nrow(CDT)){
  p_values1[i] = t.test(log(group1[i,]+1),log(group2[i,]+1),alternative='two.sided')$p.value
}
hist(p_values1,breaks = 15)

summary(p_values1)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.    NA's 
 0.0001  0.2539  0.4368  0.4842  0.7154  0.9997    1225 

There are 1225 genes that have no expression in any Naive CD4+ T cells. Remove these genes.

CDT = CDT[-which((rowSums(CDT)==0)),]

Again, t-test does not apply here since for a lot of genes, only one cell has non-zero read counts among two groups.

Now let’s apply ROTS method for scDE, which is one of the best performance method tested in Sonenson and Delorenzi.

# First Normalize the counts by Trimmed Mean of M-values as required by ROTS. Then apply ROTS.
group = rep(0,ncol(CDT))
group[group1_idx] = 1
library(ROTS)
#ROTS_results = ROTS(data = CDTnorm, groups = group , B = 100 , K = 500 , seed = 1234)
load('data/ROTS_results.RData')
summary(ROTS_results, fdr = 0.05)
ROTS results: 

Number of resamplings:  100 

a1:                     4.6 
a2:                     1 
Top list size:          390 
Reproducibility value:  0.1662051 
Z-score:                5.651558 

0 rows satisfy the condition.
     Row ROTS-statistic pvalue FDR
hist(ROTS_results$pvalue,breaks = 15)

RUV methods

First apply on NULL data then add signals to genes using Poisson thinning.

Randomly split 709 cells to two groups.

library(vicar)

set.seed(12345)
group1_idx = sample(1:ncol(CDT),ncol(CDT)/2)
group1 = CDT[,group1_idx]
group2 = CDT[,-group1_idx]

group_indicator = rep(0,ncol(CDT))
group_indicator[group1_idx] = 1

X = model.matrix(~group_indicator)
CDT = as.matrix(CDT)

Y = t((CDT))

#num_sv     <- sva::num.sv(dat = t(Y), mod = X, method = "be")
#num_sv_l   <- sva::num.sv(dat = t(Y), mod = X, method = "leek")

num_sv = 3
#num_sv_l

The number of estimated surrogate variables is 3.

eps=0.01
Y = log(Y+eps)
mout = mouthwash(Y,X,k=num_sv,cov_of_interest = 2,include_intercept = FALSE)
Running mouthwash on 709 x 2 matrix X and 709 x 12488 matrix Y.
 - Computing independent basis using QR decomposition.
 - Computation took 23.891 seconds.
 - Running additional preprocessing steps.
 - Computation took 0.002 seconds.
 - Running second step of mouthwash:
    + Estimating model parameters using EM.
    + Computation took 134.018 seconds.
    + Generating adaptive shrinkage (ash) output.
    + Computation took 1.46 seconds.
 - Second step took 136.331 seconds.
 - Estimating additional hidden confounders.
 - Computation took 2.991 seconds.
save(mout,file = 'data/mout_null.RData')
#load('data/mout_null.RData')
mout$pi0
[1] 0.9991927
library(cate)
#library(leapp)

cate_cate   <- cate::cate.fit(X.primary = X[, 2, drop = FALSE], X.nuis = X[, -2, drop = FALSE],
                              Y = Y, r = num_sv, adj.method = "rr")
save(cate_cate,file = 'data/cate_cate_null.RData')
#load('data/cate_cate_null.RData')
# this method is vey slow!
#leapp_leapp <- leapp::leapp(data = t(Y), pred.prim = X[, 2, drop = FALSE], 
#                            pred.covar = X[, -2, drop = FALSE], num.fac = num_sv)

sva_sva     <- sva::sva(dat = t(Y), mod = X, mod0 = X[, -2, drop = FALSE], n.sv = num_sv)
Number of significant surrogate variables is:  3 
Iteration (out of 5 ):1  2  3  4  5  
save(sva_sva,file = 'data/sva_sva_null.RData')
#load('data/sva_sva_null.RData')
X.sva <- cbind(X, sva_sva$sv)
lmout <- limma::lmFit(object = t(Y), design = X.sva)
eout  <- limma::eBayes(lmout)
svaout           <- list()
svaout$betahat   <- lmout$coefficients[, 2]
svaout$sebetahat <- lmout$stdev.unscaled[, 2] * sqrt(eout$s2.post)
svaout$pvalues   <- eout$p.value[, 2]

hist(svaout$pvalues,breaks=15)

ks.test(svaout$pvalues,'punif',0,1)

    One-sample Kolmogorov-Smirnov test

data:  svaout$pvalues
D = 0.074756, p-value < 2.2e-16
alternative hypothesis: two-sided
hist(cate_cate$beta.p.value,breaks = 15)

ks.test(cate_cate$beta.p.value,'punif',0,1)

    One-sample Kolmogorov-Smirnov test

data:  cate_cate$beta.p.value
D = 0.072026, p-value < 2.2e-16
alternative hypothesis: two-sided

Add some signal to the NULL dataset.

library(seqgendiff)
#tt = thin_diff(round(cell16), design_fixed = X[,2,drop=FALSE])
set.seed(12345)
thinout = thin_2group(round(CDT),0.9,signal_fun = stats::rexp,signal_params = list(rate=0.5))

#check null groups

group1 = CDT[,which(thinout$designmat==1)]
group2 = CDT[,which(thinout$designmat==0)]
## for each gene, run a two-sample t test

#p_values1 = c()
#for(i in 1:nrow(CDT)){
#  p_values1[i] = t.test(group1[i,],group2[i,],alternative='two.sided')$p.value
#}
#ks.test(p_values1,'punif',0,1)
#hist(p_values1,breaks = 15)

Y = t(thinout$mat)

remove.idx = which(colSums(Y)==0)

Y = log(Y[,-remove.idx]+eps)

X = model.matrix(~thinout$designmat)

#num_sv     <- sva::num.sv(dat = t(Y), mod = X, method = "be")
#num_sv_l   <- sva::num.sv(dat = t(Y), mod = X, method = "leek")

num_sv = 3
#num_sv_l

mean(abs(thinout$coef) < 10^-6)
[1] 0.899984
mout = mouthwash(Y,X,k=num_sv,cov_of_interest = 2,include_intercept = FALSE)
Running mouthwash on 709 x 2 matrix X and 709 x 12446 matrix Y.
 - Computing independent basis using QR decomposition.
 - Computation took 22.124 seconds.
 - Running additional preprocessing steps.
 - Computation took 0 seconds.
 - Running second step of mouthwash:
    + Estimating model parameters using EM.
    + Computation took 179.905 seconds.
    + Generating adaptive shrinkage (ash) output.
    + Computation took 1.419 seconds.
 - Second step took 182.303 seconds.
 - Estimating additional hidden confounders.
 - Computation took 2.433 seconds.
save(mout,file = 'data/mout_mid.RData')
mout$pi0
[1] 0.9822051
#load('data/mout_mid.RData')

#bout <- backwash(Y = Y, X = X, k = num_sv, cov_of_interest = 2, include_intercept = FALSE)
#save(bout,file = 'data/bout_mid.RData')
#bout$pi0


cate_cate = cate::cate.fit(X.primary = X[, 2, drop = FALSE], X.nuis = X[, -2, drop = FALSE],
                              Y = Y, r = num_sv, adj.method = "rr")
save(cate_cate,file = 'data/cate_cate_mid.RData')
#load('data/cate_cate_mid.RData')
sva_sva     <- sva::sva(dat = t(Y), mod = X, mod0 = X[, -2, drop = FALSE], n.sv = num_sv)
Number of significant surrogate variables is:  3 
Iteration (out of 5 ):1  2  3  4  5  
save(sva_sva,file = 'data/sva_sva_mid.RData')
#load('data/sva_sva_mid.RData')
X.sva <- cbind(X, sva_sva$sv)
lmout <- limma::lmFit(object = t(Y), design = X.sva)
eout  <- limma::eBayes(lmout)
svaout           <- list()
svaout$betahat   <- lmout$coefficients[, 2]
svaout$sebetahat <- lmout$stdev.unscaled[, 2] * sqrt(eout$s2.post)
svaout$pvalues   <- eout$p.value[, 2]

which_null = c(1*(abs(thinout$coef[-remove.idx]) < 10^-6))



# plot ROC curve
roc_out <- list(
  pROC::roc(response = which_null, predictor = c(mout$result$lfdr)),
  #pROC::roc(response = which_null, predictor = c(bout$result$lfdr)),
  pROC::roc(response = which_null, predictor = c(cate_cate$beta.p.value)),
  pROC::roc(response = which_null, predictor = c(svaout$pvalues)))
name_vec <- c("MOUTHWASH", "CATErr", "SVA")
names(roc_out) <- name_vec

sout <- lapply(roc_out, function(x) { data.frame(TPR = x$sensitivities, FPR = 1 - x$specificities)})
for (index in 1:length(sout)) {
  sout[[index]]$Method <- name_vec[index]
}
longdat <- do.call(rbind, sout)

shortdat <- dplyr::filter(longdat, Method == "MOUTHWASH" |
                            Method == "CATErr" | Method == "SVA" | Method == "LEAPP")
library(ggplot2)
ggplot(data = shortdat, mapping = aes(x = FPR, y = TPR, col = Method)) +
  geom_path() + theme_bw() + ggtitle("ROC Curves")

auc_vec <- sapply(roc_out, FUN = function(x) { x$auc })
knitr::kable(sort(auc_vec, decreasing = TRUE), col.names = "AUC", digits = 3)
AUC
SVA 0.743
CATErr 0.734
MOUTHWASH 0.630
# estimate pi0
method_list <- list()
method_list$CATErr           <- list()
method_list$CATErr$betahat   <- c(cate_cate$beta)
method_list$CATErr$sebetahat <- c(sqrt(cate_cate$beta.cov.row * c(cate_cate$beta.cov.col)) / sqrt(nrow(X)))

method_list$SVA             <- list()
method_list$SVA$betahat     <- c(svaout$betahat)
method_list$SVA$sebetahat   <- c(svaout$sebetahat)

ashfit <- lapply(method_list, FUN = function(x) { ashr::ash(x$betahat, x$sebetahat)})
api0 <- sapply(ashfit, FUN = ashr::get_pi0)
api0 <- c(api0, MOUTHWASH = mout$pi0)
#api0 <- c(api0, BACKWASH = bout$pi0)

knitr::kable(sort(api0, decreasing = TRUE), col.names = "Estimate of Pi0")
Estimate of Pi0
MOUTHWASH 0.9822051
SVA 0.9766238
CATErr 0.1653960

Stronger signal: rexp(,rate = 0.2)

set.seed(12345)
thinout = thin_2group(round(CDT),0.9,signal_fun = stats::rexp,signal_params = list(rate=0.2))



Y = t(thinout$mat)

remove.idx = which(colSums(Y)==0)

Y = log(Y[,-remove.idx]+eps)

X = model.matrix(~thinout$designmat)



mean(abs(thinout$coef) < 10^-6)
[1] 0.899984
mout = mouthwash(Y,X,k=num_sv,cov_of_interest = 2,include_intercept = FALSE)
Running mouthwash on 709 x 2 matrix X and 709 x 12431 matrix Y.
 - Computing independent basis using QR decomposition.
 - Computation took 22.332 seconds.
 - Running additional preprocessing steps.
 - Computation took 0.001 seconds.
 - Running second step of mouthwash:
    + Estimating model parameters using EM.
    + Computation took 178.899 seconds.
    + Generating adaptive shrinkage (ash) output.
    + Computation took 1.437 seconds.
 - Second step took 181.393 seconds.
 - Estimating additional hidden confounders.
 - Computation took 2.378 seconds.
save(mout,file = 'data/mout_high.RData')
mout$pi0
[1] 0.9662333
#bout <- backwash(Y = Y, X = X, k = num_sv, cov_of_interest = 2, include_intercept = FALSE)
#save(bout,file = 'data/bout_high.RData')
#bout$pi0


cate_cate = cate::cate.fit(X.primary = X[, 2, drop = FALSE], X.nuis = X[, -2, drop = FALSE],
                              Y = Y, r = num_sv, adj.method = "rr")
save(cate_cate,file = 'data/cate_cate_high.RData')
sva_sva     <- sva::sva(dat = t(Y), mod = X, mod0 = X[, -2, drop = FALSE], n.sv = num_sv)
Number of significant surrogate variables is:  3 
Iteration (out of 5 ):1  2  3  4  5  
save(sva_sva,file = 'data/sva_sva_high.RData')
X.sva <- cbind(X, sva_sva$sv)
lmout <- limma::lmFit(object = t(Y), design = X.sva)
eout  <- limma::eBayes(lmout)
svaout           <- list()
svaout$betahat   <- lmout$coefficients[, 2]
svaout$sebetahat <- lmout$stdev.unscaled[, 2] * sqrt(eout$s2.post)
svaout$pvalues   <- eout$p.value[, 2]

which_null = c(1*(abs(thinout$coef[-remove.idx]) < 10^-6))

roc_out <- list(
  pROC::roc(response = which_null, predictor = c(mout$result$lfdr)),
  #pROC::roc(response = which_null, predictor = c(bout$result$lfdr)),
  pROC::roc(response = which_null, predictor = c(cate_cate$beta.p.value)),
  pROC::roc(response = which_null, predictor = c(svaout$pvalues)))
name_vec <- c("MOUTHWASH", "CATErr", "SVA")
names(roc_out) <- name_vec

sout <- lapply(roc_out, function(x) { data.frame(TPR = x$sensitivities, FPR = 1 - x$specificities)})
for (index in 1:length(sout)) {
  sout[[index]]$Method <- name_vec[index]
}
longdat <- do.call(rbind, sout)

shortdat <- dplyr::filter(longdat, Method == "MOUTHWASH" | 
                            Method == "CATErr" | Method == "SVA" | Method == "LEAPP")
ggplot(data = shortdat, mapping = aes(x = FPR, y = TPR, col = Method)) +
  geom_path() + theme_bw() + ggtitle("ROC Curves")

auc_vec <- sapply(roc_out, FUN = function(x) { x$auc })
knitr::kable(sort(auc_vec, decreasing = TRUE), col.names = "AUC", digits = 3)
AUC
SVA 0.827
CATErr 0.814
MOUTHWASH 0.685
method_list <- list()
method_list$CATErr           <- list()
method_list$CATErr$betahat   <- c(cate_cate$beta)
method_list$CATErr$sebetahat <- c(sqrt(cate_cate$beta.cov.row * c(cate_cate$beta.cov.col)) / sqrt(nrow(X)))

method_list$SVA             <- list()
method_list$SVA$betahat     <- c(svaout$betahat)
method_list$SVA$sebetahat   <- c(svaout$sebetahat)

ashfit <- lapply(method_list, FUN = function(x) { ashr::ash(x$betahat, x$sebetahat)})
api0 <- sapply(ashfit, FUN = ashr::get_pi0)
api0 <- c(api0, MOUTHWASH = mout$pi0)
#api0 <- c(api0, BACKWASH = bout$pi0)

knitr::kable(sort(api0, decreasing = TRUE), col.names = "Estimate of Pi0")
Estimate of Pi0
MOUTHWASH 0.9662333
SVA 0.4528195
CATErr 0.1373782

sessionInfo()
R version 3.6.1 (2019-07-05)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.6

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.6/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] parallel  stats4    stats     graphics  grDevices utils     datasets 
[8] methods   base     

other attached packages:
 [1] ggplot2_3.2.1               seqgendiff_1.1.1           
 [3] cate_1.1                    vicar_0.1-10               
 [5] ROTS_1.12.0                 Seurat_3.1.2               
 [7] MAST_1.10.0                 SingleCellExperiment_1.6.0 
 [9] SummarizedExperiment_1.14.1 DelayedArray_0.10.0        
[11] BiocParallel_1.18.1         matrixStats_0.55.0         
[13] Biobase_2.44.0              GenomicRanges_1.36.1       
[15] GenomeInfoDb_1.20.0         IRanges_2.18.3             
[17] S4Vectors_0.22.1            BiocGenerics_0.30.0        

loaded via a namespace (and not attached):
  [1] reticulate_1.13        R.utils_2.9.0          tidyselect_0.2.5      
  [4] lme4_1.1-21            RSQLite_2.1.2          AnnotationDbi_1.46.1  
  [7] htmlwidgets_1.5.1      grid_3.6.1             Rtsne_0.15            
 [10] pROC_1.15.3            munsell_0.5.0          codetools_0.2-16      
 [13] mutoss_0.1-12          ica_1.0-2              future_1.15.1         
 [16] withr_2.1.2            colorspace_1.4-1       leapp_1.2             
 [19] highr_0.8              knitr_1.25             pscl_1.5.2            
 [22] ROCR_1.0-7             gbRd_0.4-11            listenv_0.8.0         
 [25] labeling_0.3           Rdpack_0.11-0          git2r_0.26.1          
 [28] GenomeInfoDbData_1.2.1 mixsqp_0.1-97          mnormt_1.5-5          
 [31] bit64_0.9-7            rprojroot_1.3-2        vctrs_0.2.0           
 [34] TH.data_1.0-10         xfun_0.10              R6_2.4.0              
 [37] doParallel_1.0.15      rsvd_1.0.2             bitops_1.0-6          
 [40] assertthat_0.2.1       promises_1.1.0         SDMTools_1.1-221.2    
 [43] scales_1.0.0           multcomp_1.4-12        gtable_0.3.0          
 [46] npsurv_0.4-0           globals_0.12.5         sva_3.32.1            
 [49] sandwich_2.5-1         svd_0.5                workflowr_1.5.0       
 [52] rlang_0.4.0            zeallot_0.1.0          genefilter_1.66.0     
 [55] splines_3.6.1          lazyeval_0.2.2         yaml_2.2.0            
 [58] reshape2_1.4.3         abind_1.4-5            backports_1.1.5       
 [61] httpuv_1.5.2           tools_3.6.1            gplots_3.0.1.1        
 [64] RColorBrewer_1.1-2     ggridges_0.5.2         TFisher_0.2.0         
 [67] Rcpp_1.0.2             plyr_1.8.4             zlibbioc_1.30.0       
 [70] purrr_0.3.2            RCurl_1.95-4.12        pbapply_1.4-2         
 [73] ashr_2.2-38            cowplot_1.0.0          zoo_1.8-6             
 [76] ggrepel_0.8.1          cluster_2.1.0          fs_1.3.1              
 [79] magrittr_1.5           data.table_1.12.6      lmtest_0.9-37         
 [82] RANN_2.6.1             truncnorm_1.0-8        mvtnorm_1.0-11        
 [85] SQUAREM_2017.10-1      whisker_0.4            fitdistrplus_1.0-14   
 [88] lsei_1.2-0             evaluate_0.14          xtable_1.8-4          
 [91] XML_3.98-1.20          gridExtra_2.3          compiler_3.6.1        
 [94] tibble_2.1.3           KernSmooth_2.23-15     crayon_1.3.4          
 [97] minqa_1.2.4            R.oo_1.23.0            htmltools_0.4.0       
[100] mgcv_1.8-29            corpcor_1.6.9          later_1.0.0           
[103] tidyr_1.0.0            RcppParallel_4.4.4     DBI_1.0.0             
[106] MASS_7.3-51.4          boot_1.3-23            Matrix_1.2-17         
[109] R.methodsS3_1.7.1      gdata_2.18.0           metap_1.2             
[112] igraph_1.2.4.1         pkgconfig_2.0.3        sn_1.5-4              
[115] numDeriv_2016.8-1.1    plotly_4.9.1           foreach_1.4.7         
[118] annotate_1.62.0        blme_1.0-4             multtest_2.40.0       
[121] XVector_0.24.0         ruv_0.9.7.1            bibtex_0.4.2          
[124] stringr_1.4.0          digest_0.6.21          sctransform_0.2.1     
[127] RcppAnnoy_0.0.13       tsne_0.1-3             rmarkdown_1.16        
[130] leiden_0.3.1           uwot_0.1.5             gtools_3.8.1          
[133] nloptr_1.2.1           lifecycle_0.1.0        nlme_3.1-141          
[136] jsonlite_1.6           viridisLite_0.3.0      limma_3.40.6          
[139] pillar_1.4.2           lattice_0.20-38        httr_1.4.1            
[142] plotrix_3.7-7          survival_2.44-1.1      glue_1.3.1            
[145] esaBcv_1.2.1           png_0.1-7              iterators_1.0.12      
[148] bit_1.1-14             stringi_1.4.3          blob_1.2.0            
[151] memoise_1.1.0          caTools_1.17.1.2       dplyr_0.8.3           
[154] irlba_2.3.3            future.apply_1.4.0     ape_5.3