utils::globalVariables(c(
"AU", "n", "TC", "PY", "AU.x", "year", "Author",
"TCpY", "freq"
))
#' Top-Authors' Productivity over Time
#'
#' It calculates and plots the author production (in terms of number of publications) over the time.
#' @param M is a bibliographic data frame obtained by \code{\link{convert2df}} function.
#' @param k is a integer. It is the number of top authors to analyze and plot. Default is \code{k = 10}.
#' @param graph is logical. If TRUE the function plots the author production over time graph. Default is \code{graph = TRUE}.
#' @return The function \code{authorProdOverTime} returns a list containing two objects:
#' \tabular{lll}{
#' \code{dfAU} \tab \tab is a data frame\cr
#' \code{dfpapersAU}\tab \tab is a data frame\cr
#' \code{graph} \tab \tab a ggplot object}
#'
#' @examples
#' data(scientometrics, package = "bibliometrixData")
#' res <- authorProdOverTime(scientometrics, k = 10)
#' print(res$dfAU)
#' plot(res$graph)
#'
#' @seealso \code{\link{biblioAnalysis}} function for bibliometric analysis
#' @seealso \code{\link{summary}} method for class '\code{bibliometrix}'
#'
#' @export
#'
authorProdOverTime <- function(M, k = 10, graph = TRUE) {
if (!("DI" %in% names(M))) {
M$DI <- "NA"
}
M$TC <- as.numeric(M$TC)
M$PY <- as.numeric(M$PY)
M <- M[!is.na(M$PY), ] # remove rows with missing value in PY
Y <- as.numeric(substr(Sys.time(), 1, 4))
listAU <- (strsplit(M$AU, ";"))
nAU <- lengths(listAU)
df <- data.frame(AU = trimws(unlist(listAU)), SR = rep(M$SR, nAU))
AU <- df %>%
group_by(AU) %>%
count() %>%
arrange(desc(n)) %>%
ungroup()
k <- min(k, nrow(AU))
AU <- AU %>%
slice_head(n = k)
df <- df %>%
right_join(AU, by = "AU") %>%
left_join(M, by = "SR") %>%
select("AU.x", "PY", "TI", "SO", "DI", "TC") %>%
mutate(TCpY = TC / (Y - PY + 1)) %>%
group_by(AU.x) %>%
mutate(n = length(AU.x)) %>%
ungroup() %>%
rename(
Author = AU.x,
year = PY,
DOI = DI
) %>%
arrange(desc(n), desc(year)) %>%
select(-n)
df2 <- dplyr::group_by(df, Author, year) %>%
dplyr::summarise(freq = length(year), TC = sum(TC), TCpY = sum(TCpY)) %>%
as.data.frame()
df2$Author <- factor(df2$Author, levels = AU$AU[1:k])
x <- c(0.5, 1.5 * k / 10)
y <- c(min(df$year), min(df$year) + diff(range(df2$year)) * 0.125)
data("logo", envir = environment())
logo <- grid::rasterGrob(logo, interpolate = TRUE)
g <- ggplot(df2, aes(x = Author, y = year, text = paste("Author: ", Author, "\nYear: ", year, "\nN. of Articles: ", freq, "\nTotal Citations per Year: ", round(TCpY, 2)))) +
geom_point(aes(alpha = TCpY, size = freq), color = "dodgerblue4") +
scale_size(range = c(2, 6)) +
scale_alpha(range = c(0.3, 1)) +
scale_y_continuous(breaks = seq(min(df2$year), max(df2$year), by = 2)) +
guides(size = guide_legend(order = 1, "N.Articles"), alpha = guide_legend(order = 2, "TC per Year")) +
theme(
legend.position = "right",
text = element_text(color = "#444444"),
panel.background = element_rect(fill = "#FFFFFF"),
plot.title = element_text(size = 24),
axis.title = element_text(size = 14, color = "#555555"),
axis.title.y = element_text(vjust = 1, angle = 90) # , face="bold")
, axis.title.x = element_text(hjust = .95) # ,face="bold")
, axis.text.x = element_text(face = "bold", angle = 90),
axis.text.y = element_text(face = "bold")
# ,axis.line.x = element_line(color="black", size=1)
, axis.line.x = element_line(color = "grey50", linewidth = 0.5),
panel.grid.major.x = element_blank(),
panel.grid.major.y = element_line(linewidth = .2, color = "grey90")
) +
# coord_fixed(ratio = 2/1) +
labs(
title = "Authors' Production over Time",
x = "Author",
y = "Year"
) +
geom_line(data = df2, aes(x = Author, y = year, group = Author), size = 1.0, color = "firebrick4", alpha = 0.3) +
scale_x_discrete(limits = rev(levels(df2$Author))) +
coord_flip() +
annotation_custom(logo, xmin = x[1], xmax = x[2], ymin = y[1], ymax = y[2])
df$DOI <- as.character(df$DOI)
res <- list(dfAU = df2, dfPapersAU = df, graph = g)
if (isTRUE(graph)) {
plot(g)
}
return(res)
}
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