Difference between revisions of "Ggplot2"

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== Scatterplot ==
 
== Scatterplot ==
[https://wilkelab.org/SDS375/slides/overplotting.html?s=09#1 Handling overlapping points]
+
[https://wilkelab.org/SDS375/slides/overplotting.html?s=09#1 Handling overlapping points] (slides) and the ebook [https://clauswilke.com/dataviz/overlapping-points.html Fundamentals of Data Visualization] by Claus O. Wilke.
  
 
== Line plots ==
 
== Line plots ==

Revision as of 16:15, 6 May 2021

ggplot2

Books

The Grammar of Graphics

  • Data: Raw data that we'd like to visualize
  • Geometrics: shapes that we use to visualize data
  • Aesthetics: Properties of geometries (size, color, etc)
  • Scales: Mapping between geometries and aesthetics

Scatterplot aesthetics

geom_point(). The aesthetics is geom dependent.

  • x, y
  • shape
  • color
  • size. It is not always to put 'size' inside aes(). See an example at Legend layout.
  • alpha
library(ggplot2)
library(tidyverse)
set.seed(1)
x1 <- rbinom(100, 1, .5) - .5
x2 <- c(rnorm(50, 3, .8)*.1, rnorm(50, 8, .8)*.1)
x3 <- x1*x2*2
# x=1:100, y=x1, x2, x3
tibble(x=1:length(x1), T=x1, S=x2, I=x3) %>% 
  tidyr::pivot_longer(-x) %>% 
  ggplot(aes(x=x, y=value, group=name)) + 
  geom_point(aes(color=name))

# Cf
matplot(1:length(x1), cbind(x1, x2, x3), pch=16, 
        col=c('cornflowerblue', 'springgreen3', 'salmon'))

Online tutorials

Help

> library(ggplot2)
Need help? Try Stackoverflow: https://stackoverflow.com/tags/ggplot2

Gallery

Some examples

Examples from 'R for Data Science' book - Aesthetic mappings

ggplot(data = mpg) + 
  geom_point(mapping = aes(x = displ, y = hwy))
  # the 'mapping' is the 1st argument for all geom_* functions, so we can safely skip it.
# template
ggplot(data = <DATA>) + 
  <GEOM_FUNCTION>(mapping = aes(<MAPPINGS>))

# add another variable through color, size, alpha or shape
ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy, color = class))

ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy, size = class))

ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy, alpha = class))

ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy, shape = class))

ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy), color = "blue")

# add another variable through facets
ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy)) + 
  facet_wrap(~ class, nrow = 2)

# add another 2 variables through facets
ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy)) + 
  facet_grid(drv ~ cyl)

Examples from 'R for Data Science' book - Geometric objects, lines and smoothers

How to Add a Regression Line to a ggplot?

# Points
ggplot(data = mpg) + 
  geom_point(aes(x = displ, y = hwy)) # we can add color to aes()

# Line plot
ggplot() +
  geom_line(aes(x, y))  # we can add color to aes()

# Smoothed
# 'size' controls the line width
ggplot(data = mpg) + 
  geom_smooth(aes(x = displ, y = hwy), size=1) 

# Points + smoother, add transparency to points, remove se
# We add transparency if we need to make smoothed line stands out
#                    and points less significant
# We move aes to the '''mapping''' option in ggplot()
ggplot(data = mpg, mapping = aes(x = displ, y = hwy)) + 
  geom_point(alpha=1/10) +
  geom_smooth(se=FALSE)    

# Colored points + smoother
ggplot(data = mpg, aes(x = displ, y = hwy)) + 
  geom_point(aes(color = class)) + 
  geom_smooth()

Examples from 'R for Data Science' book - Transformation, bar plot

# y axis = counts
# bar plot
ggplot(data = diamonds) + 
  geom_bar(aes(x = cut))
# Or
ggplot(data = diamonds) + 
  stat_count(aes(x = cut))

# y axis = proportion
ggplot(data = diamonds) + 
  geom_bar(aes(x = cut, y = ..prop.., group = 1))

# bar plot with 2 variables
ggplot(data = diamonds) + 
  geom_bar(aes(x = cut, fill = clarity))

facet_wrap and facet_grid to create a panel of plots

Color palette

Color picker

https://github.com/daattali/colourpicker

Color names

ColorHexa

colorspace package

colorspace: A Toolbox for Manipulating and Assessing Colors and Palettes

scale_fill_discrete_qualitative(palette) and an example. The palette selections are different from scale_fill_XXX(). Note that the number of classes can be arbitrary in scale_fill_discrete_qualitative().

Colour related aesthetics: colour, fill and alpha

https://ggplot2.tidyverse.org/reference/aes_colour_fill_alpha.html

Scatterplot with large number of points: alpha

smoothScatter with ggplot2

ggplot(aes(x, y)) +
    geom_point(alpha=.1) 

Combine colors and shapes in legend

  • https://ggplot2-book.org/scales.html#scale-details In order for legends to be merged, they must have the same name.
    df <- data.frame(x = 1:3, y = 1:3, z = c("a", "b", "c"))
    ggplot(df, aes(x, y)) + geom_point(aes(shape = z, colour = z), size=4)
    
  • How to Work with Scales in a ggplot2 in R. This solution is better since it allows to change the legend title. Just make sure the title name we put in both scale_* functions are the same.
    ggplot(mtcars, aes(x=hp, y=mpg)) +
       geom_point(aes(shape=factor(cyl), colour=factor(cyl))) +
       scale_shape_discrete("Cylinders") +
       scale_colour_discrete("Cylinders")
    

ggplot2::scale functions and scales packages

  • Scales control the mapping from data to aesthetics. They take your data and turn it into something that you can see, like size, colour, position or shape.
  • Scales also provide the tools that let you read the plot: the axes and legends.

ggplot2::scale - axes/axis, legend

https://ggplot2-book.org/scales.html

Naming convention: scale_AestheticName_NameDataType where

  • AestheticName can be x, y, color, fill, size, shape, ...
  • NameDataType can be continuous, discrete, manual or gradient.

Examples:

  • See Figure 12.1: Axis and legend components on the book ggplot2: Elegant Graphics for Data Analysis
    # Set x-axis label
    scale_x_discrete("Car type")   # or a shortcut xlab() or labs()
    scale_x_continuous("Displacement")
    
    # Set legend title
    scale_colour_discrete("Drive\ntrain")    # or a shortcut labs()
    
    # Change the default color
    scale_color_brewer()
    
    # Change the axis scale
    scale_x_sqrt()
    
    # Change breaks and their labels
    scale_x_continuous(breaks = c(2000, 4000), labels = c("2k", "4k"))
    
    # Relabel the breaks in a categorical scale
    scale_y_discrete(labels = c(a = "apple", b = "banana", c = "carrot"))
    
  • How to change the color in geom_point or lines in ggplot
    ggplot() + 
      geom_point(data = data, aes(x = time, y = y, color = sample),size=4) +
      scale_color_manual(values = c("A" = "black", "B" = "red"))
    
    ggplot(data = data, aes(x = time, y = y, color = sample)) + 
      geom_point(size=4) + 
      geom_line(aes(group = sample)) + 
      scale_color_manual(values = c("A" = "black", "B" = "red"))
    

ylim and xlim in ggplot2 in axes

https://stackoverflow.com/questions/3606697/how-to-set-limits-for-axes-in-ggplot2-r-plots or the Zooming part of the cheatsheet

Use one of the following

  • + scale_x_continuous(limits = c(-5000, 5000))
  • + coord_cartesian(xlim = c(-5000, 5000))
  • + xlim(-5000, 5000)

Emulate ggplot2 default color palette

It is just equally spaced hues around the color wheel. Emulate ggplot2 default color palette

Answer 1

gg_color_hue <- function(n) {
  hues = seq(15, 375, length = n + 1)
  hcl(h = hues, l = 65, c = 100)[1:n]
}

n = 4
cols = gg_color_hue(n)

dev.new(width = 4, height = 4)
plot(1:n, pch = 16, cex = 2, col = cols)

Answer 2 (better, it shows the color values in HEX). It should be read from left to right and then top to down.

scales package

library(scales)
show_col(hue_pal()(4)) # ("#F8766D", "#7CAE00", "#00BFC4", "#C77CFF")
                       # (Salmon, Christi, Iris Blue, Heliotrope)
show_col(hue_pal()(2)) # ("#F8767D", "#00BFC4") = (salmon, iris blue) 
           # see https://www.htmlcsscolor.com/ for color names

See also the last example in ggsurv() where the KM plots have 4 strata. The colors can be obtained by scales::hue_pal()(4) with hue_pal()'s default arguments.

R has a function called colorName() to convert a hex code to color name; see roloc package.

transform scales

How to make that crazy Fox News y axis chart with ggplot2 and scales

Class variables

"Set1" is a good choice. See RColorBrewer::display.brewer.all()

Heatmap for single channel

https://scales.r-lib.org/

# White <----> Blue
RColorBrewer::display.brewer.pal(n = 8, name = "Blues")

Heatmap for dual channels

http://www.sthda.com/english/wiki/colors-in-r

library(RcolorBrewer)
# Red <----> Blue
display.brewer.pal(n = 8, name = 'RdBu')
# Hexadecimal color specification 
brewer.pal(n = 8, name = "RdBu")

plot(1:8, col=brewer_pal(palette = "RdBu")(8), pch=20, cex=4)

# Blue <----> Red
plot(1:8, col=rev(brewer_pal(palette = "RdBu")(8)), pch=20, cex=4)

Twopalette.svg

Themes and background for ggplot2

Background

  • Export plot in .png with transparent background in base R plot.
    x = c(1, 2, 3)
    op <- par(bg=NA)
    plot (x)
    
    dev.copy(png,'myplot.png')
    dev.off()
    par(op)
    
  • Transparent background with ggplot2
    library(ggplot2)
    data("airquality")
    
    p <- ggplot(airquality, aes(Solar.R, Temp)) +
         geom_point() +
         geom_smooth() +
         # set transparency
         theme(
            panel.grid.major = element_blank(), 
            panel.grid.minor = element_blank(),
            panel.background = element_rect(fill = "transparent",colour = NA),
            plot.background = element_rect(fill = "transparent",colour = NA)
            )
    p
    ggsave("airquality.png", p, bg = "transparent")
    
  • ggplot2 theme background color and grids
    ggplot() + geom_bar(aes(x=, fill=y)) +
               theme(panel.background=element_rect(fill='purple')) + 
               theme(plot.background=element_blank())
    
    ggplot() + geom_bar(aes(x=, fill=y)) + 
               theme(panel.background=element_blank()) + 
               theme(plot.background=element_blank()) # minimal background like base R
               # the grid lines are not gone; they are white so it is the same as the background
    
    ggplot() + geom_bar(aes(x=, fill=y)) + 
               theme(panel.background=element_blank()) + 
               theme(plot.background=element_blank()) +
               theme(panel.grid.major.y = element_line(color="grey"))
               # draw grid line on y-axis only
    
    ggplot() + geom_bar() +
               theme_bw()
    
    ggplot() + geom_bar() +
               theme_minimal()
    
    ggplot() + geom_bar() +
               theme_void()
    
    ggplot() + geom_bar() +
               theme_dark()
    

ggthmr

ggthmr package

ggsci

https://nanx.me/ggsci/

Font size

Change Font Size of ggplot2 Plot in R (5 Examples) | Axis Text, Main Title & Legend

Rotate x-axis labels

theme(axis.text.x = element_text(angle = 90)

Add axis on top or right hand side

Remove labels

Plotting with ggplot: : adding titles and axis names

ggthemes package

https://cran.r-project.org/web/packages/ggthemes/index.html

ggplot() + geom_bar() +
           theme_solarized()   # sun color in the background

theme_excel()
theme_wsj()
theme_economist()
theme_fivethirtyeight()

rsthemes

rsthemes

thematic

thematic, Top R tips and news from RStudio Global 2021

Common plots

Scatterplot

Handling overlapping points (slides) and the ebook Fundamentals of Data Visualization by Claus O. Wilke.

Line plots

Ridgeline plots

Histogram

Histograms is a special case of bar plots. Instead of drawing each unique individual values as a bar, a histogram groups close data points into bins.

ggplot(data = txhousing, aes(x = median)) +
  geom_histogram()  # adding 'origin =0' if we don't expect negative values.
                    # adding 'bins=10' to adjust the number of bins
                    # adding 'binwidth=10' to adjust the bin width

Histogram vs barplot from deeply trivial.

Boxplot

Be careful that if we added scale_y_continuous(expand = c(0,0), limits = c(0,1)) to the code, it will change the boxplot if some data is outside the range of (0, 1). The console gives a warning message in this case.

Base R method

Box Plots - R Base Graphs

dim(df) # 112436 x 2
mycol <- c("#F8766D", "#7CAE00", "#00BFC4", "#C77CFF")
# mycol defines colors of 4 levels in df$Method (a factor)
boxplot(df$value ~ df$Method, col = mycol, xlab="Method")

Color fill/scale_fill_XXX

n <- 100
k <- 12
set.seed(1234)
cond <- factor(rep(LETTERS[1:k], each=n))
rating <- rnorm(n*k)
dat <- data.frame(cond = cond, rating = rating)

p <- ggplot(dat, aes(x=cond, y=rating, fill=cond)) + 
     geom_boxplot() 

p + scale_fill_hue() + labs(title="hue default") # Same as only p 
p + scale_fill_hue(l=40, c=35) + labs(title="hue options")
p + scale_fill_brewer(palette="Dark2") + labs(title="Dark2")
p + colorspace::scale_fill_discrete_qualitative(palette = "Dark 3") + labs(title="Dark 3")
p + scale_fill_brewer(palette="Accent") + labs(title="Accent")
p + scale_fill_brewer(palette="Pastel1") + labs(title="Pastel1")
p + scale_fill_brewer(palette="Set1") + labs(title="Set1")
p + scale_fill_brewer(palette="Paired") + labs(title="Paired")
# cbbPalette <- c("#000000", "#E69F00", "#56B4E9", "#009E73", "#F0E442", "#0072B2", "#D55E00", "#CC79A7")
# p + scale_fill_manual(values=cbbPalette)

Scalefill.png

ColorBrewer palettes RColorBrewer::display.brewer.all() to display all brewer palettes.

Reference from ggplot2. scale_fill_binned, scale_fill_brewer, scale_fill_continuous, scale_fill_date, scale_fill_datetime, scale_fill_discrete, scale_fill_distiller, scale_fill_gradient, scale_fill_gradientc, scale_fill_gradientn, scale_fill_grey, scale_fill_hue, scale_fill_identity, scale_fill_manual, scale_fill_ordinal, scale_fill_steps, scale_fill_steps2, scale_fill_stepsn, scale_fill_viridis_b, scale_fill_viridis_c, scale_fill_viridis_d

Jittering

What is a boxplot

# Only 1 variable
ggplot(data.frame(Wi), aes(y = Wi)) + 
  geom_boxplot()

# Two variable, one of them is a factor
ggplot() + geom_jitter(mapping = aes(x, y))

# Box plot
ggplot() + geom_boxplot(mapping = aes(x, y))
# df2 is n x 2 
ggplot(df2, aes(x=nboot, y=boot)) +
  geom_boxplot(outlier.shape=NA) + #avoid plotting outliers twice
  geom_jitter(aes(color=nboot), position=position_jitter(width=.2, height=0, seed=1)) +
  labs(title="", y = "", x = "nboot")

If we omit the outlier.shape=NA option in geom_boxplot(), we will get the following plot.

Jitterboxplot.png

Groups of boxplots

How To Make Grouped Boxplots with ggplot2?. Use the fill parameter such as

mydata %>%
  ggplot(aes(x=Factor1, y=Response, fill=factor(Factor2))) +   
  geom_boxplot() 

Violin plot

library(ggplot2)
ggplot(midwest, aes(state, area)) + geom_violin() + ggforce::geom_sina()

Violinplot.png

Kernel density plot

  • Overlay histograms with density plots
    library(ggplot2); library(tidyr)
    x <- data.frame(v1=rnorm(100), v2=rnorm(100,1,1), 
                    v3=rnorm(100, 0,2))
    data <- pivot_longer(x, cols=1:3)
    ggplot(data, aes(x=value, fill=name)) +
      geom_histogram(aes(y=..density..), alpha=.25) + 
      stat_density(geom="line", aes(color=name, linetype=name))
    ggplot(data, aes(x=value, fill=name, col =name)) +
      geom_density(alpha = .4)
    

Bivariate analysis with ggpair

Correlation in R: Pearson & Spearman with Matrix Example

GGally::ggpairs

barplot

Ordered barplot and facet

ggplot(df, aes(x=reorder(x, -y), y=y)) + geom_bar(stat = 'identity')

ggplot(df, aes(x=reorder(x, desc(y)), y=y)), geom_col()

Back to back barplot

Flip x and y axes

coord_flip()

Rotate x-axis labels

ggplot(mydf) + geom_col(aes(x = model, y=value, fill = method), position="dodge")+
  theme(axis.text.x = element_text(angle = 45, hjust=1))

Starts at zero

Starting bars and histograms at zero in ggplot2

scale_y_continuous(expand = c(0,0), limits = c(0, YourLimit))

Polygon and map plot

https://ggplot2.tidyverse.org/reference/geom_polygon.html

Step function

Connect observations: geom_path(), geom_step()

Example: KM curves (without legend)

library(survival)
sf <- survfit(Surv(time, status) ~ x, data = aml)
sf
str(sf) # the first 10 forms one strata and the rest 10 forms the other
ggplot() + 
  geom_step(aes(x=c(0, sf$time[1:10]), y=c(1, sf$surv[1:10])), 
            col='red') + 
  scale_x_continuous('Time', limits = c(0, 161)) + 
  scale_y_continuous('Survival probability', limits = c(0, 1)) +
  geom_step(aes(x=c(0, sf$time[11:20]), y=c(1, sf$surv[11:20])), 
            col='black') 
# cf:  plot(sf, col = c('red', 'black'), mark.time=FALSE)

Same example but with legend (see Construct a manual legend for a complicated plot)

cols <- c("NEW"="#f04546","STD"="#3591d1")
ggplot() + 
  geom_step(aes(x=c(0, sf$time[1:10]), y=c(1, sf$surv[1:10]), col='NEW')) +
  scale_x_continuous('Time', limits = c(0, 161)) + 
  scale_y_continuous('Survival probability', limits = c(0, 1)) +
  geom_step(aes(x=c(0, sf$time[11:20]), y=c(1, sf$surv[11:20]), col='STD')) + 
  scale_colour_manual(name="Treatment", values = cols)

Coefficients, intervals, errorbars

Comparing similarities / differences between groups

comparing similarities / differences between groups

Special plots

Dot plot & forest plot

Bump plot: plot ranking over time

https://github.com/davidsjoberg/ggbump

Gauge plots

Aesthetics

  • We can create a new aesthetic name in aes(aesthetic = variable) function; for example, the "text2" below. In this case "text2" name will not be shown; only the original variable will be used.
    library(plotly)
    g <- ggplot(tail(iris), aes(Petal.Length, Sepal.Length, text2=Species)) + geom_point()
    ggplotly(g, tooltip = c("Petal.Length", "text2"))
    

group

https://ggplot2.tidyverse.org/reference/aes_group_order.html

GUI/Helper packages

ggedit & ggplotgui – interactive ggplot aesthetic and theme editor

esquisse (French, means 'sketch'): creating ggplot2 interactively

https://cran.rstudio.com/web/packages/esquisse/index.html

A 'shiny' gadget to create 'ggplot2' charts interactively with drag-and-drop to map your variables. You can quickly visualize your data accordingly to their type, export to 'PNG' or 'PowerPoint', and retrieve the code to reproduce the chart.

The interface introduces basic terms used in ggplot2:

  • x, y,
  • fill (useful for geom_bar, geom_rect, geom_boxplot, & geom_raster, not useful for scatterplot),
  • color (edges for geom_bar, geom_line, geom_point),
  • size,
  • facet, split up your data by one or more variables and plot the subsets of data together.

It does not include all features in ggplot2. At the bottom of the interface,

  • Labels & title & caption.
  • Plot options. Palette, theme, legend position.
  • Data. Remove subset of data.
  • Export & code. Copy/save the R code. Export file as PNG or PowerPoint.

ggcharts

https://cran.r-project.org/web/packages/ggcharts/index.html

ggeasy

ggx

https://github.com/brandmaier/ggx Create ggplot in natural language

plotly

R web → plotly

ggconf: Simpler Appearance Modification of 'ggplot2'

https://github.com/caprice-j/ggconf

Plotting individual observations and group means

https://drsimonj.svbtle.com/plotting-individual-observations-and-group-means-with-ggplot2

subplot

Adding/Inserting an image to ggplot2

Inserting an image to ggplot2: See annotation_custom.

See also ggbernie which uses a different way ggplot2::layer() and a self-defined geom (geometric object).

Easy way to mix multiple graphs on the same page

annotation_custom

grid

gridExtra

Force a regular plot object into a Grob for use in grid.arrange

gridGraphics package

make one panel blank/create a placeholder

https://stackoverflow.com/questions/20552226/make-one-panel-blank-in-ggplot2

labs for x and y axes

x and y labels

https://stackoverflow.com/questions/10438752/adding-x-and-y-axis-labels-in-ggplot2 or the Labels part of the cheatsheet

You can set the labels with xlab() and ylab(), or make it part of the scale_*.* call.

labs(x = "sample size", y = "ngenes (glmnet)")

scale_x_discrete(name="sample size")
scale_y_continuous(name="ngenes (glmnet)", limits=c(100, 500))

Change tick mark labels

ggplot2 axis ticks : A guide to customize tick marks and labels

name-value pairs

See several examples (color, fill, size, ...) from opioid prescribing habits in texas.

Prevent sorting of x labels

See Change the order of a discrete x scale.

The idea is to set the levels of x variable.

junk   # n x 2 table
colnames(junk) <- c("gset", "boot")
junk$gset <- factor(junk$gset, levels = as.character(junk$gset))
ggplot(data = junk, aes(x = gset, y = boot, group = 1)) + 
  geom_line() + 
  theme(axis.text.x=element_text(color = "black", angle=30, vjust=.8, hjust=0.8))

Legends

Legend title

  • labs() function
    p <- ggplot(df, aes(x, y)) + geom_point(aes(colour = z))
    p + labs(x = "X axis", y = "Y axis", colour = "Colour\nlegend")
    
  • scale_colour_manual()
    scale_colour_manual("Treatment", values = c("black", "red"))
    
  • scale_color_discrete() and scale_shape_discrete(). See Combine colors and shapes in legend.
    df <- data.frame(x = 1:3, y = 1:3, z = c("a", "b", "c"))
    ggplot(df, aes(x, y)) + geom_point(aes(shape = z, colour = z), size=5) + 
      scale_color_discrete('new title') + scale_shape_discrete('new title')
    

Layout: move the legend from right to top/bottom of the plot or hide it

gg + theme(legend.position = "top")

gg + theme(legend.position="none")

Guide functions for finer control

https://ggplot2-book.org/scales.html#guide-functions The guide functions, guide_colourbar() and guide_legend(), offer additional control over the fine details of the legend.

guide_legend() allows the modification of legends for scales, including fill, color, and shape.

This function can be used in scale_fill_manual(), scale_fill_continuous(), ... functions.

scale_fill_manual(values=c("orange", "blue"), 
                  guide=guide_legend(title = "My Legend Title",
                                     nrow=1,  # multiple items in one row
                                     label.position = "top", # move the texts on top of the color key
                                     keywidth=2.5)) # increase the color key width

The problem with the default setting is it leaves a lot of white space above and below the legend. To change the position of the entire legend to the bottom of the plot, we use theme().

theme(legend.position = 'bottom')

Legend symbol background

ggplot() + geom_point(aes(x, y, color, size)) +
           theme(legend.key = element_blank())
           # remove the symbol background in legend

Construct a manual legend for a complicated plot

https://stackoverflow.com/a/17149021

Legend size

How to Change Legend Size in ggplot2 (With Examples)

ggtitle()

Centered title

See the Legends part of the cheatsheet.

ggtitle("MY TITLE") +
  theme(plot.title = element_text(hjust = 0.5))

Subtitle

ggtitle("My title",
        subtitle = "My subtitle")

margins

https://stackoverflow.com/a/10840417

Aspect ratio

?coord_fixed

p <- ggplot(mtcars, aes(mpg, wt)) + geom_point()
p + coord_fixed() # plot is compressed horizontally
p  # fill up plot region

Time series plot

Multiple lines plot https://stackoverflow.com/questions/14860078/plot-multiple-lines-data-series-each-with-unique-color-in-r

set.seed(45)
nc <- 9
df <- data.frame(x=rep(1:5, nc), val=sample(1:100, 5*nc), 
                   variable=rep(paste0("category", 1:nc), each=5))
# plot
# http://colorbrewer2.org/#type=qualitative&scheme=Paired&n=9
ggplot(data = df, aes(x=x, y=val)) + 
    geom_line(aes(colour=variable)) + 
    scale_colour_manual(values=c("#a6cee3", "#1f78b4", "#b2df8a", "#33a02c", "#fb9a99", "#e31a1c", "#fdbf6f", "#ff7f00", "#cab2d6"))

Versus old fashion

dat <- matrix(runif(40,1,20),ncol=4) # make data
matplot(dat, type = c("b"),pch=1,col = 1:4) #plot
legend("topleft", legend = 1:4, col=1:4, pch=1) # optional legend

Github style calendar plot

geom_bar(), geom_col(), stat_count()

https://ggplot2.tidyverse.org/reference/geom_bar.html

geom_col(position = 'dodge')  # same as 
geom_bar(stat = 'identity', position = 'dodge')

geom_bar() can not specify the y-axis. To specify y-axis, use geom_col().

ggplot() + geom_col(mapping = aes(x, y))

Add numbers to the plot

An example

stat_function()

geom_area()

The Pfizer-Biontech Vaccine May Be A Lot More Effective Than You Think

geom_segment()

Line segments, arrows and curves

Cf annotate("segment", ...)

Square shaped plot

ggplot() + theme(aspect.ratio=1) # do not adjust xlim, ylim

xylim <- range(c(x, y))
ggplot() + coord_fixed(xlim=xylim, ylim=xylim) 

Use geom_line() to create a square bracket to annotate the plot

Barchart with Significance Tests

geom_errorbar(): error bars

set.seed(301)
x <- rnorm(10)
SE <- rnorm(10)
y <- 1:10

par(mfrow=c(2,1))
par(mar=c(0,4,4,4))
xlim <- c(-4, 4)
plot(x[1:5], 1:5, xlim=xlim, ylim=c(0+.1,6-.1), yaxs="i", xaxt = "n", ylab = "", pch = 16, las=1)
mtext("group 1", 4, las = 1, adj = 0, line = 1) # las=text rotation, adj=alignment, line=spacing
par(mar=c(5,4,0,4))
plot(x[6:10], 6:10, xlim=xlim, ylim=c(5+.1,11-.1), yaxs="i", ylab ="", pch = 16, las=1, xlab="")
arrows(x[6:10]-SE[6:10], 6:10, x[6:10]+SE[6:10], 6:10, code=3, angle=90, length=0)
mtext("group 2", 4, las = 1, adj = 0, line = 1)

Stklnpt.svg

geom_rect(), geom_bar()

Note that we can use scale_fill_manual() to change the 'fill' colors (scheme/palette). The 'fill' parameter in geom_rect() is only used to define the discrete variable.

ggplot(data=) +
  geom_bar(aes(x=, fill=)) +
  scale_fill_manual(values = c("orange", "blue"))

Circle

Circle in ggplot2 ggplot(data.frame(x = 0, y = 0), aes(x, y)) + geom_point(size = 25, pch = 1)

Ellipse

How can a data ellipse be superimposed on a ggplot2 scatterplot?. Hint: use the ellipse package.

Annotation

geom_hline(), geom_vline()

geom_hline(yintercept=1000)
geom_vline(xintercept=99)

text annotations, annotate() and geom_text(): ggrepel package

  • https://ggplot2-book.org/annotations.html
    annotate("text", label="Toyota", x=3, y=100)
    annotate("segment", x = 2.5, xend = 4, y = 15, yend = 25, colour = "blue", size = 2)
    
    geom_text(aes(x, y, label), data, size, vjust, hjust, nudge_x)
    
  • Use the nudge_y parameter to avoid the overlap of the point and the text such as
    ggplot() + geom_point() +
               geom_text(aes(x, y, label), color='red', data, nudge_y=1)
    
  • What do hjust and vjust do when making a plot using ggplot? 0 means left-justified 1 means right-justified.

Text wrap

ggplot2 is there an easy way to wrap annotation text?

p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()

# Solution 1: Not work with Chinese characters
wrapper <- function(x, ...) paste(strwrap(x, ...), collapse = "\n")
# The a label
my_label <- "Some arbitrarily larger text"
# and finally your plot with the label
p + annotate("text", x = 4, y = 25, label = wrapper(my_label, width = 5))

# Solution 2: Not work with Chinese characters
library(RGraphics)
library(ggplot2)
p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()
grob1 <-  splitTextGrob("Some arbitrarily larger text")
p + annotation_custom(grob = grob1,  xmin = 3, xmax = 4, ymin = 25, ymax = 25) 

# Solution 3: stringr::str_wrap()
my_label <- "太極者無極而生。陰陽之母也。動之則分。靜之則合。無過不及。隨曲就伸。人剛我柔謂之走。我順人背謂之黏。"
p <- ggplot() + geom_point() + xlim(0, 400) + ylim(0, 300) # 400x300 e-paper
p + annotate("text", x = 0, y = 200, hjust=0, size=5,
             label = stringr::str_wrap(my_label, width =30)) +
    theme_bw () + 
    theme(panel.grid.major = element_blank(), 
          panel.grid.minor = element_blank(), 
          panel.border = element_blank(),
          axis.title = element_blank(), 
          axis.text = element_blank(),
          axis.ticks = element_blank()) 

ggtext

ggtext: Improved text rendering support for ggplot2

Other geoms

Exploring other {ggplot2} geoms

Fonts

Adding Custom Fonts to ggplot in R

Lines of best fit

Lines of best fit

Save the plots

My experience is ggsave() is better than png() because ggsave() makes the text larger when we save a file with a higher resolution.

...
ggsave("filename.png", object, width=8, height=4)
# vs
png("filename.png", width=1200, height=600)
...
dev.off()

ggsave() We can specify dpi to increase the resolution. For example,

g1 <- ggplot(data = mydf) 
g1
ggsave("myfile.png", g1, height = 7, width = 8, units = "in", dpi = 500)

I got an error - Error in loadNamespace(name) : there is no package called ‘svglite’. After I install the package, everything works fine.

ggsave("raw-output.bmp", p, width=4, height=3, dpi = 100)
# Will generate 4*100 x 3*100 pixel plot

Multiple pages in pdf

https://stackoverflow.com/a/53698682. The key is to save the plot in an object and use the print() function.

pdf("FileName", onefile = TRUE)
for(i in 1:I) {
  p <- ggplot()
  print(p)
}
dev.off()

graphics::smoothScatter

smoothScatter with ggplot2

Other tips

Tips and tricks for working with images and figures in R Markdown documents

Ten Simple Rules for Better Figures

Ten Simple Rules for Better Figures

BBC

Add your brand to ggplot graph

You Need to Start Branding Your Graphs. Here's How, with ggplot!

Animation and gganimate

ggstatsplot

ggstatsplot: ggplot2 Based Plots with Statistical Details

Write your own ggplot2 function: rlang

Some packages depend on ggplot2

dittoSeq from Bicoonductor

Meme

Python

plotnine: A Grammar of Graphics for Python.

plotnine is an implementation of a grammar of graphics in Python, it is based on ggplot2. The grammar allows users to compose plots by explicitly mapping data to the visual objects that make up the plot.

The Hitchhiker’s Guide to Plotnine