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#' Calculate G+C from unlabeled buoyant density
#'
#' See Hungate et al., 2015 for more details
#'
#' @param Wlight A vector with >=1 weighted mean BD from
#' 'light' gradient fractions
#' @return numeric value (fractional G+C; Gi)
#'
calc_Gi = function(Wlight){
if(length(Wlight) > 1){
Gi = sapply(Wlight, calc_Gi)
} else{
Gi = 1 / 0.083506 * (Wlight - 1.646057)
}
return(Gi)
}
#' Calculate the theoretical maximum molecular weight of fully-labeled DNA
#'
#' See Hungate et al., 2015 for more details
#'
#' @param Mlight The molecular wight of unlabeled DNA
#' @param isotope The isotope for which the DNA is labeled with ('13C' or '18O')
#' @param Gi The G+C content of unlabeled DNA
#' @return numeric value: maximum molecular weight of fully-labeled DNA
#'
calc_Mheavymax = function(Mlight, isotope='13C', Gi=NA){
isotope = toupper(isotope)
if(isotope=='13C'){
Mhm = -0.4987282 * Gi + 9.974564 + Mlight
} else
if(isotope=='18O'){
Mhm = 12.07747 + Mlight
} else {
stop('isotope not recognized')
}
return(Mhm)
}
#' Calculate atom fraction excess
#'
#' See Hungate et al., 2015 for more details
#'
#' @param Mlab The molecular wight of labeled DNA
#' @param Mlight The molecular wight of unlabeled DNA
#' @param Mheavymax The theoretical maximum molecular weight of fully-labeled DNA
#' @param isotope The isotope for which the DNA is labeled with ('13C' or '18O')
#' @return numeric value: atom fraction excess (A)
#'
calc_atom_excess = function(Mlab, Mlight, Mheavymax, isotope='13C'){
isotope=toupper(isotope)
if(isotope=='13C'){
x = 0.01111233
} else
if(isotope=='18O'){
x = 0.002000429
} else {
stop('isotope not recognized')
}
A = (Mlab - Mlight) / (Mheavymax - Mlight) * (1 - x)
return(A)
}
#' Reformat a phyloseq object of qSIP_atom_excess analysis
#'
#' @param physeq A phyloseq object
#' @param control_expr An expression for identifying unlabeled control
#' samples in the phyloseq object (eg., "Substrate=='12C-Con'")
#' @param treatment_rep Which column in the phyloseq sample data designates
#' replicate treatments
#' @return numeric value: atom fraction excess (A)
#'
qSIP_atom_excess_format = function(physeq, control_expr, treatment_rep){
# formatting input
cols = c('IS_CONTROL', 'Buoyant_density', treatment_rep)
df_OTU = phyloseq2table(physeq,
include_sample_data=TRUE,
sample_col_keep=cols,
control_expr=control_expr)
# removing 'infinite' BD values
tmp = colnames(df_OTU)
df_OTU = df_OTU %>%
dplyr::mutate_(Buoyant_density = "as.numeric(as.character(Buoyant_density))",
Count = "as.numeric(as.character(Count))") %>%
dplyr::filter_('! is.infinite(Buoyant_density)') %>%
dplyr::filter_('! is.na(Buoyant_density)') %>%
as.data.frame
colnames(df_OTU) = tmp
# return
return(df_OTU)
}
#' Calculate atom fraction excess using q-SIP method
#'
#' @param physeq A phyloseq object
#' @param control_expr Expression used to identify control samples based on sample_data.
#' @param treatment_rep Which column in the phyloseq sample data designates
#' replicate treatments
#' @param isotope The isotope for which the DNA is labeled with ('13C' or '18O')
#' @param df_OTU_W Keep NULL
#'
#' @return A list of 2 data.frame objects. 'W' contains
#' the weighted mean buoyant density (W) values for each OTU in
#' each treatment/control. 'A' contains the atom fraction excess
#' values for each OTU. For the 'A' table, the 'Z' column is buoyant
#' density shift, and the 'A' column is atom fraction excess.
#'
#' @export
#'
#' @examples
#' # tranforming values
#' physeq_rep3_t = OTU_qPCR_trans(physeq_rep3, physeq_rep3_qPCR)
#'
#' \dontrun{
#' # BD shift (Z) & atom excess (A)
#' atomX = qSIP_atom_excess(physeq_rep3_t,
#' control_expr='Treatment=="12C-Control"',
#' treatment_rep='Replicate')
#' }
#'
qSIP_atom_excess = function(physeq,
control_expr,
treatment_rep=NULL,
isotope='13C',
df_OTU_W=NULL){
# formatting input
if(is.null(df_OTU_W)){
no_boot = TRUE
} else {
no_boot = FALSE
}
if(no_boot){
df_OTU = qSIP_atom_excess_format(physeq, control_expr, treatment_rep)
if(nrow(df_OTU) == 0){
stop('No rows in OTU table after qSIP_atom_excess_format(). Check control_exp & treatment_rep')
}
# BD shift (Z)
df_OTU_W = df_OTU %>%
# weighted mean buoyant density (W)
dplyr::mutate_(Buoyant_density = "as.numeric(as.character(Buoyant_density))",
Count = "as.numeric(as.character(Count))") %>%
dplyr::group_by_('IS_CONTROL', 'OTU', treatment_rep) %>%
dplyr::summarize_(W = "stats::weighted.mean(Buoyant_density, Count, na.rm=TRUE)") %>%
dplyr::ungroup()
}
df_OTU_s = df_OTU_W %>%
# mean W of replicate gradients
dplyr::group_by_('IS_CONTROL', 'OTU') %>%
dplyr::summarize_(Wm = "mean(W, na.rm=TRUE)") %>%
# BD shift (Z)
dplyr::group_by_('OTU') %>%
dplyr::mutate_(IS_CONTROL = "ifelse(IS_CONTROL==TRUE, 'Wlight', 'Wlab')") %>%
tidyr::spread("IS_CONTROL", "Wm") %>%
dplyr::mutate_(Z = "Wlab - Wlight") %>%
dplyr::ungroup()
# atom excess (A)
## pt1
dots = list(~calc_Gi(Wlight))
dots = stats::setNames(dots, "Gi")
df_OTU_s = df_OTU_s %>%
mutate_(.dots=dots) %>%
mutate_(Mlight = "0.496 * Gi + 307.691")
## pt2
MoreArgs = list(isotope=isotope)
dots = list(~mapply(calc_Mheavymax, Mlight=Mlight, Gi=Gi, MoreArgs=MoreArgs))
dots = stats::setNames(dots, "Mheavymax")
df_OTU_s = df_OTU_s %>%
dplyr::mutate_(.dots=dots)
## pt3
dots = list(~mapply(calc_atom_excess, Mlab=Mlab, Mlight=Mlight,
Mheavymax=Mheavymax, MoreArgs=MoreArgs))
dots = stats::setNames(dots, "A")
df_OTU_s = df_OTU_s %>%
dplyr::mutate_(Mlab = "(Z / Wlight + 1) * Mlight") %>%
dplyr::mutate_(.dots=dots)
## flow control: bootstrap
if(no_boot){
return(list(W=df_OTU_W, A=df_OTU_s))
} else {
return(df_OTU_s)
}
}
# sampling with replacement from control & treatment for each OTU
sample_W = function(df, n_sample){
n_light = n_sample[1]
n_lab = n_sample[2]
# parsing df
df_light = df[df$IS_CONTROL==TRUE,]
df_lab = df[df$IS_CONTROL==FALSE,]
# sampling
if(length(df_light$W) > 1){
W_light = base::sample(df_light$W, n_light, replace=TRUE)
} else {
W_light = rep(df_light$W, n_light)
}
if(length(df_lab$W) > 1){
W_lab = base::sample(df_lab$W, n_lab, replace=TRUE)
} else {
W_lab = rep(df_lab$W, n_lab)
}
# creating new data.frames
df_light = data.frame(IS_CONTROL=TRUE,
#OTU=rep(otu, n_light),
W = W_light)
df_lab = data.frame(IS_CONTROL=FALSE,
#OTU=rep(otu, n_lab),
W = W_lab)
return(rbind(df_light, df_lab))
}
# shuffling weighted mean densities (W)
.qSIP_bootstrap = function(atomX,
isotope='13C',
n_sample=c(3,3),
bootstrap_id = 1){
# making a new (subsampled with replacement) dataset
n_sample = c(3,3) # control, treatment
dots = stats::setNames(list(~lapply(data, sample_W, n_sample=n_sample)), "ret")
df_OTU_W = atomX$W %>%
dplyr::group_by_("OTU") %>%
tidyr::nest() %>%
dplyr::mutate_(.dots=dots) %>%
dplyr::select_("-data") %>%
tidyr::unnest()
# calculating atom excess
atomX = qSIP_atom_excess(physeq=NULL,
df_OTU_W=df_OTU_W,
control_expr=NULL,
treatment_rep=NULL,
isotope=isotope)
atomX$bootstrap_id = bootstrap_id
return(atomX)
}
#' Calculate bootstrap CI for atom fraction excess using q-SIP method
#'
#' @param atomX A list object created by \code{qSIP_atom_excess()}
#' @param isotope The isotope for which the DNA is labeled with ('13C' or '18O')
#' @param n_sample A vector of length 2.
#' The sample size for data resampling (with replacement) for 1) control samples
#' and 2) treatment samples.
#' @param n_boot Number of bootstrap replicates.
#' @param a A numeric value. The alpha for calculating confidence intervals.
#' @param parallel Parallel processing. See \code{.parallel} option in
#' \code{dplyr::mdply()} for more details.
#'
#' @return A data.frame of atom fraction excess values (A) and
#' atom fraction excess confidence intervals.
#'
#' @export
#'
#' @examples
#' # tranforming values
#' physeq_rep3_t = OTU_qPCR_trans(physeq_rep3, physeq_rep3_qPCR)
#'
#' \dontrun{
#' # BD shift (Z) & atom excess (A)
#' atomX = qSIP_atom_excess(physeq_rep3_t,
#' control_expr='Treatment=="12C-Con"',
#' treatment_rep='Replicate')
#'
#' # bootstrapping in parallel
#' doParallel::registerDoParallel(2)
#' df_atomX_boot = qSIP_bootstrap(atomX, parallel=TRUE)
#' head(df_atomX_boot)
#' }
#'
qSIP_bootstrap = function(atomX, isotope='13C', n_sample=c(3,3),
n_boot=10, parallel=FALSE, a=0.1){
# atom excess for each bootstrap replicate
df_boot_id = data.frame(bootstrap_id = 1:n_boot)
df_boot = plyr::mdply(df_boot_id, .qSIP_bootstrap,
atomX = atomX,
isotope=isotope,
n_sample=n_sample,
.parallel=parallel)
# calculating atomX CIs for each OTU
mutate_call1 = lazyeval::interp(~ stats::quantile(A, a/2, na.rm=TRUE),
A = as.name("A"))
mutate_call2 = lazyeval::interp(~ stats::quantile(A, 1-a/2, na.rm=TRUE),
A = as.name("A"))
dots = stats::setNames(list(mutate_call1, mutate_call2), c("A_CI_low", "A_CI_high"))
df_boot = df_boot %>%
dplyr::group_by_("OTU") %>%
dplyr::summarize_(.dots=dots)
# combining with atomX summary data
df_boot = dplyr::inner_join(atomX$A, df_boot, c('OTU'='OTU'))
return(df_boot)
}
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