# Line Plots - R Base Graphs

Previously, we described the essentials of R programming and provided quick start guides for importing data into **R**.

**line plots**in R. The function

**plot**() or

**lines**() can be used to create a line plot.

# Pleleminary tasks

**Launch RStudio**as described here: Running RStudio and setting up your working directory**Prepare your data**as described here: Best practices for preparing your data and save it in an external .txt tab or .csv files**Import your data**into**R**as described here: Fast reading of data from txt|csv files into R: readr package.

# R base functions: plot() and lines()

The simplified format of **plot**() and **lines**() is as follow.

```
plot(x, y, type = "l", lty = 1)
lines(x, y, type = "l", lty = 1)
```

**x, y**: coordinate vectors of points to join**type**: character indicating the type of plotting. Allowed values are:- “p” for points
- “l” for lines
- “b” for both points and lines
- “c” for empty points joined by lines
- “o” for overplotted points and lines
- “s” and “S” for stair steps
- “n” does not produce any points or lines

**lty**: line types. Line types can either be specified as an integer (0=blank, 1=solid (default), 2=dashed, 3=dotted, 4=dotdash, 5=longdash, 6=twodash) or as one of the character strings “blank”, “solid”, “dashed”, “dotted”, “dotdash”, “longdash”, or “twodash”, where “blank” uses ‘invisible lines’ (i.e., does not draw them).

# Create some data

```
# Create some variables
x <- 1:10
y1 <- x*x
y2 <- 2*y1
```

We’ll plot a plot with two lines: **lines**(x, y1) and **lines**(x, y2).

Note that the function **lines**() can not produce a plot on its own. However, it can be used to add **lines**() on an existing graph. This means that, first you have to use the function **plot**() to create an empty graph and then use the function **lines**() to add lines.

# Basic line plots

```
# Create a basic stair steps plot
plot(x, y1, type = "S")
# Show both points and line
plot(x, y1, type = "b", pch = 19,
col = "red", xlab = "x", ylab = "y")
```

# Plots with multiple lines

```
# Create a first line
plot(x, y1, type = "b", frame = FALSE, pch = 19,
col = "red", xlab = "x", ylab = "y")
# Add a second line
lines(x, y2, pch = 18, col = "blue", type = "b", lty = 2)
# Add a legend to the plot
legend("topleft", legend=c("Line 1", "Line 2"),
col=c("red", "blue"), lty = 1:2, cex=0.8)
```

# See also

# Infos

This analysis has been performed using **R statistical software** (ver. 3.2.4).

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