programming – Page 2 – Quantum Forest

Functions with multiple results in tidyverse

Mobile phone antenna in church (Photo: Luis, click to enlarge).

I have continued playing with the tidyverse for different parts of a couple of projects. Often I need to apply a function by groups of observations; sometimes, that function returns more than a single number. It could be something like for each group fit a distribution and return the distribution parameters. Or, simpler for the… Continue reading Functions with multiple results in tidyverse

Turtles all the way down

Door in Valparaíso.

One of the main uses for R is for exploration and learning. Let's say that I wanted to learn simple linear regression (the bread and butter of statistics) and see how the formulas work. I could simulate a simple example and fit the regression with R:

library(arm)  # For display() 

# Simulate 5 observations
set.seed(50)
x <- 1:5
y <- 2 + 3*x + rnorm(5, mean = 0, sd = 3)

# Fit regression
reg <- lm(y ~ x, dat)
display(reg)

# lm(formula = y ~ x, data = dat)
#             coef.est coef.se
# (Intercept) 3.99     3.05   
# x           2.04     0.92   
# ---
# n = 5, k = 2
# residual sd = 2.91, R-Squared = 0.62

# Plot it
plot(y ~ x)
abline(coef(reg))

library(arm) # For display()

# Simulate 5 observations

set.seed(50)

x <- 1:5

y <- 2 + 3*x + rnorm(5, mean = 0, sd = 3)

# Fit regression

reg <- lm(y ~ x, dat)

display(reg)

# lm(formula = y ~ x, data = dat)

# coef.est coef.se

# (Intercept) 3.99 3.05

# x 2.04 0.92

# ---

# n = 5, k = 2

# residual sd = 2.91, R-Squared = 0.62

# Plot it

plot(y ~ x)

abline(coef(reg))

The formulas for the intercept ($latex b_0$) and… Continue reading Turtles all the way down

Old dog and the tidyverse

Trees in a carpark (Photo: Luis, click to enlarge).

I started using R ages ago and have happily lived in mostly-base-R for data manipulation. Once in a while I move to something that makes a big difference, like ggplot2 in 2010 or Rmarkdown in 2015, but the set of packages I use for data + plotting hasn't seen many changes. I have to confess… Continue reading Old dog and the tidyverse

Left-to-right

When I write code I'm often amazed by the direction of the statements. I mean, we read and write left-to-right except when we assign statements to a variable. So here we are, doing our business, slowly working in a sentence and, puff!, we get this insight from the future and we assign it to our… Continue reading Left-to-right

Sometimes I feel (some) need for speed

I'm the first to acknowledge that most of my code could run faster. The truth of the matter is that, in essence, I write 'quickies': code that will run once or twice, so there is no incentive to spend days or hours in shaving seconds of a computation. Most analyses of research data fall in… Continue reading Sometimes I feel (some) need for speed