R 简明教程

R - Line Graphs

折线图是一种通过在点之间绘制线段来连接一系列点的图形。这些点按其一个坐标值（通常是 x 坐标）排序。折线图通常用于识别数据中的趋势。

A line chart is a graph that connects a series of points by drawing line segments between them. These points are ordered in one of their coordinate (usually the x-coordinate) value. Line charts are usually used in identifying the trends in data.

R 中的 plot() 函数用于创建折线图。

The plot() function in R is used to create the line graph.

Syntax

在 R 中创建折线图的基本语法为：

The basic syntax to create a line chart in R is −

plot(v,type,col,xlab,ylab)

以下是所用参数的描述 -

Following is the description of the parameters used −

  1. v is a vector containing the numeric values.

  2. type takes the value "p" to draw only the points, "l" to draw only the lines and "o" to draw both points and lines.

  3. xlab is the label for x axis.

  4. ylab is the label for y axis.

  5. main is the Title of the chart.

  6. col is used to give colors to both the points and lines.

Example

使用输入向量和类型参数“O”创建简单的折线图。以下脚本将在当前 R 工作目录中创建和保存折线图。

A simple line chart is created using the input vector and the type parameter as "O". The below script will create and save a line chart in the current R working directory.

# Create the data for the chart.
v <- c(7,12,28,3,41)

# Give the chart file a name.
png(file = "line_chart.jpg")

# Plot the bar chart.
plot(v,type = "o")

# Save the file.
dev.off()

当我们执行上述代码时，会产生以下结果 -

When we execute the above code, it produces the following result −

line chart

Line Chart Title, Color and Labels

可以通过使用其他参数来扩展折线图的功能。我们给点和线添加颜色，给图表添加标题并给轴添加标签。

The features of the line chart can be expanded by using additional parameters. We add color to the points and lines, give a title to the chart and add labels to the axes.

Example

# Create the data for the chart.
v <- c(7,12,28,3,41)

# Give the chart file a name.
png(file = "line_chart_label_colored.jpg")

# Plot the bar chart.
plot(v,type = "o", col = "red", xlab = "Month", ylab = "Rain fall",
   main = "Rain fall chart")

# Save the file.
dev.off()

当我们执行上述代码时，会产生以下结果 -

When we execute the above code, it produces the following result −

line chart label colored

Multiple Lines in a Line Chart

可以在同一张图表上绘制多条线，方法是使用 lines() 函数。

More than one line can be drawn on the same chart by using the *lines()*function.

在绘制完第一条线后，lines() 函数可以使用一个额外的向量作为输入，在图表中绘制第二条线。

After the first line is plotted, the lines() function can use an additional vector as input to draw the second line in the chart,

# Create the data for the chart.
v <- c(7,12,28,3,41)
t <- c(14,7,6,19,3)

# Give the chart file a name.
png(file = "line_chart_2_lines.jpg")

# Plot the bar chart.
plot(v,type = "o",col = "red", xlab = "Month", ylab = "Rain fall",
   main = "Rain fall chart")

lines(t, type = "o", col = "blue")

# Save the file.
dev.off()

当我们执行上述代码时，会产生以下结果 -

When we execute the above code, it produces the following result −

line chart 2 lines