meu_tema.R

meu_tema <- function(base.size = 9, legend.text.size = 9, axis.text.size = 10, axis.title.size = 11) {

# exemplo da função lm
#ggplot(agua_agregado, aes(x = dif_pressao, y = vazao_massica_media)) +
#  geom_point() + geom_smooth(method = "lm") +
#  meu_tema() +
#  labs(x = "Diferença de Pressão (Pa)", y = "Vazão mássica (kg)") +
#  annotate("text", x = 1500, y = 0.0035, parse = TRUE, size = 3, hjust = 0.25,
#           label = lm.equation(lm(vazao_massica_media ~ dif_pressao, data = agua_agregado),
#                               digits = 10, digitsR2 = 4))

  library(ggplot2)
  library(RColorBrewer)
  library(scales)
  library(grid)
  cinza <- brewer.pal("Greys", n=9)[6]
  # Generate the colors for the chart procedurally with RColorBrewer
  palette <- brewer.pal("Greys", n=9)
  color.background = palette[2]
  color.grid.major = palette[3]
  color.axis.text = palette[6]
  color.axis.title = palette[7]
  color.title = palette[9]
  
  # Begin construction of chart
  theme_bw(base_size = base.size) +
    
    # Set the entire chart region to a light gray color
    theme(panel.background=element_rect(fill=color.background, color=color.background)) +
    theme(plot.background=element_rect(fill=color.background, color=color.background)) +
    theme(panel.border=element_rect(color=color.background)) +
    
    # Format the grid
    theme(panel.grid.major=element_line(color=color.grid.major,size=.25)) +
    theme(panel.grid.minor=element_blank()) +
    theme(axis.ticks=element_blank()) +
    
    # Format the legend, but hide by default
    theme(legend.position="none") +
    theme(legend.background = element_rect(fill=color.background)) +
    theme(legend.text = element_text(size=legend.text.size, color=color.axis.title)) +
    
    # Set title and axis labels, and format these and tick marks
    theme(plot.title=element_text(color=color.title, size=10, vjust=1.25)) +
    theme(axis.text.x=element_text(size=axis.text.size, color=color.axis.text)) +
    theme(axis.text.y=element_text(size=axis.text.size, color=color.axis.text)) +
    theme(axis.title.x=element_text(size=axis.title.size, color=color.axis.title, vjust=0)) +
    theme(axis.title.y=element_text(size=axis.title.size, color=color.axis.title, vjust=1.25)) +
    
    # remove boxes around legend symbols
    theme(legend.key = element_blank()) +
    # Plot margins
    theme(plot.margin = unit(c(0.35, 0.2, 0.3, 0.35), "cm"))
}

# adicionar equação de regressão linear no gráfico

lm.equation = function(x, digits = 4, digitsR2 = 3) {
  lm_coef <- list(a = round(coef(x)[1], digits = digits),
                  b = round(coef(x)[2], digits = digits),
                  r2 = round(summary(x)$r.squared, digits = digitsR2));
  lm_eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(R)^2~"="~r2,lm_coef)
  as.character(as.expression(lm_eq));                 
}

# definir função adicional para forçar b = 0

lm.equation0 = function(x, digits = 4, digitsR2 = 3) {
  lm_coef <- list(
    a = round(coef(x)[1], digits = digits),
    #b = round(coef(x)[2], digits = digits), # b forçado a 0
    r2 = round(summary(x)$r.squared, digits = digitsR2)
    )
  lm_eq <- substitute(italic(y) == 0 + a %.% italic(x)*","~~italic(R)^2~"="~r2,lm_coef)
  as.character(as.expression(lm_eq));                 
}


# exemplo: http://t-redactyl.io/blog/2016/05/creating-plots-in-r-using-ggplot2-part-11-linear-regression-plots.html