# Archive for July, 2015

# trunc() and floor(), round() and signif() in R

**floor** takes a single numeric argument x and returns a numeric vector containing the largest integers not greater than the corresponding elements of x.

**trunc** takes a single numeric argument x and returns a numeric vector containing the integers formed by truncating the values in x toward 0.

** round** rounds the values in its first argument to the specified number of decimal places (default 0).

** signif** rounds the values in its first argument to the specified number of significant digits.

test:

————————–

> x <- c(-5.2, -3.8, 5.2, 3.8)

>floor(x)

-6 -4 5 3

>trunc(x)

-5 -3 5 3

> x <- 3.1415

—————————-

>round(x)

3

>round(x,3)

3.142

>signif(x,3)

3.14

# Plot Histogram in R

Plot Histogram in R:

Method 1: hist(vector, breaks)

Take care for the parameter “breaks”:

according the help:

breaks: a single number giving the number of cells for the histogram.

Important: the number is a suggestion only! The breakpoints will be set to pretty values.

For example:

>data(“women”) #load dateset “women”

> hist(women$weight, breaks = 7)

If you want to have exact 7 bins, you should specify the position

>hist(women$weight, breaks=seq(min(women$weight), max(women$weight), l = 7))

so, you will get the exact 7 bins