Tag: snow

Animated Snow in R, 2.0: gganimate API update

Animated Snow in R, 2.0: gganimate API update

Last year, inspired by a tweet from Ilya Kashnitsky, I wrote a snow animation which you can read all about here

Now, this year, the old code no longer worked due to an update to the gganimate API. Hence, I was about to only refactor the code, but decided to give the whole thing a minor update. Below, you find the 2.0 version of my R snow animation.

# PACKAGES ####
pkg <- c("here", "tidyverse", "gganimate", "animation")
sapply(pkg, function(x){
if (!x %in% installed.packages()){install.packages(x)}
library(x, character.only = TRUE)
})

# CUSTOM FUNCTIONS ####
map_to_range <- function(x, from, to) {
# Shifting the vector so that min(x) == 0
x <- x - min(x)
# Scaling to the range of [0, 1]
x <- x / max(x)
# Scaling to the needed amplitude
x <- x * (to - from)
# Shifting to the needed level
x + from
}

# CONSTANTS ####
N <- 500 # number of flakes
TIMES <- 100 # number of loops
XPOS_DELTA <- 0.01
YSPEED_MIN = 0.005
YSPEED_MAX = 0.03
FLAKE_SIZE_COINFLIP = 5
FLAKE_SIZE_COINFLIP_PROB = 0.1
FLAKE_SIZE_MIN = 4
FLAKE_SIZE_MAX = 20

# INITIALIZE DATA ####
set.seed(1)

size <- runif(N) + rbinom(N, FLAKE_SIZE_COINFLIP, FLAKE_SIZE_COINFLIP_PROB) # random flake size
yspeed <- map_to_range(size, YSPEED_MIN, YSPEED_MAX)

# create storage vectors
xpos <- rep(NA, N * TIMES)
ypos <- rep(NA, N * TIMES)

# loop through simulations
for(i in seq(TIMES)){
if(i == 1){
# initiate values
xpos[1:N] <- runif(N, min = -0.1, max = 1.1)
ypos[1:N] <- runif(N, min = 1.1, max = 2)
} else {
# specify datapoints to update
first_obs <- (N * i - N + 1)
last_obs <- (N * i)
# update x position
# random shift
xpos[first_obs:last_obs] <- xpos[(first_obs-N):(last_obs-N)] - runif(N, min = -XPOS_DELTA, max = XPOS_DELTA)
# update y position
# lower by yspeed
ypos[first_obs:last_obs] <- ypos[(first_obs-N):(last_obs-N)] - yspeed
# reset if passed bottom screen
xpos <- ifelse(ypos < -0.1, runif(N), xpos) # restart at random x
ypos <- ifelse(ypos < -0.1, 1.1, ypos) # restart just above top
}
}


# VISUALIZE DATA ####
cbind.data.frame(ID = rep(1:N, TIMES)
,x = xpos
,y = ypos
,s = size
,t = rep(1:TIMES, each = N)) %>%
# create animation
ggplot() +
geom_point(aes(x, y, size = s, alpha = s), color = "white", pch = 42) +
scale_size_continuous(range = c(FLAKE_SIZE_MIN, FLAKE_SIZE_MAX)) +
scale_alpha_continuous(range = c(0.2, 0.8)) +
coord_cartesian(c(0, 1), c(0, 1)) +
theme_void() +
theme(legend.position = "none",
panel.background = element_rect("black")) +
transition_time(t) +
ease_aes('linear') ->
snow_plot

snow_anim <- animate(snow_plot, nframes = TIMES, width = 600, height = 600)

If you want to see some spin-offs of last years code:

Animated Snow in R

Animated Snow in R

Due to the recent updates to the gganimate package, the code below no longer produces the desired animation.
A working, updated version can be found here

After hearing R play the Jingle Bells tune, I really got into the holiday vibe. It made me think of Ilya Kashnitsky (homepage, twitter) his snowy image in R.

if(!"tidyverse" %in% installed.packages()) install.packages("tidyverse")

library("tidyverse")

n <- 100 
tibble(x = runif(n),  
y = runif(n),  
s = runif(n, min = 4, max = 20)) %>%
ggplot(aes(x, y, size = s)) +
geom_point(color = "white", pch = 42) +
scale_size_identity() +
coord_cartesian(c(0,1), c(0,1)) +
theme_void() +
theme(panel.background = element_rect("black"))

snow.png

This greatly fits the Christmas theme we have going here. Inspired by Ilya’s script, I decided to make an animated snowy GIF! Sure R is able to make something like the lively visualizations Daniel Shiffman (Coding Train) usually makes in Processing/JavaScript? It seems so:

snow

### ANIMATED SNOW === BY PAULVANDERLAKEN.COM
### PUT THIS FILE IN AN RPROJECT FOLDER

# load in packages
pkg <- c("here", "tidyverse", "gganimate", "animation")
sapply(pkg, function(x){
if (!x %in% installed.packages()){install.packages(x)}
library(x, character.only = TRUE)
})

# parameters
n <- 100 # number of flakes
times <- 100 # number of loops
xstart <- runif(n, max = 1) # random flake start x position
ystart <- runif(n, max = 1.1) # random flake start y position
size <- runif(n, min = 4, max = 20) # random flake size
xspeed <- seq(-0.02, 0.02, length.out = 100) # flake shift speeds to randomly pick from
yspeed <- runif(n, min = 0.005, max = 0.025) # random flake fall speed

# create storage vectors
xpos <- rep(NA, n * times)
ypos <- rep(NA, n * times)

# loop through simulations
for(i in seq(times)){
if(i == 1){
# initiate values
xpos[1:n] <- xstart
ypos[1:n] <- ystart
} else {
# specify datapoints to update
first_obs <- (n*i - n + 1)
last_obs <- (n*i)
# update x position
# random shift
xpos[first_obs:last_obs] <- xpos[(first_obs-n):(last_obs-n)] - sample(xspeed, n, TRUE)
# update y position
# lower by yspeed
ypos[first_obs:last_obs] <- ypos[(first_obs-n):(last_obs-n)] - yspeed
# reset if passed bottom screen
xpos <- ifelse(ypos < -0.1, runif(n), xpos) # restart at random x
ypos <- ifelse(ypos < -0.1, 1.1, ypos) # restart just above top
}
}

# store in dataframe
data_fluid <- cbind.data.frame(x = xpos,
y = ypos,
s = size,
t = rep(1:times, each = n))

# create animation
snow <- data_fluid %>%
ggplot(aes(x, y, size = s, frame = t)) +
geom_point(color = "white", pch = 42) +
scale_size_identity() +
coord_cartesian(c(0, 1), c(0, 1)) +
theme_void() +
theme(panel.background = element_rect("black"))

# save animation
gganimate(snow, filename = here("snow.gif"), title_frame = FALSE, interval = .1)

snowsnow.gifsnow.gif

Updates: