R 简明教程

R - Histograms

直方图表示按范围分段的变量值的频率。直方图类似于条形图，但区别在于它将值分组为连续范围。直方图中的每个条形表示该范围内存在的值的数量的高度。

A histogram represents the frequencies of values of a variable bucketed into ranges. Histogram is similar to bar chat but the difference is it groups the values into continuous ranges. Each bar in histogram represents the height of the number of values present in that range.

R 使用 hist() 函数创建直方图。该函数以向量作为输入，并使用更多参数绘制直方图。

R creates histogram using hist() function. This function takes a vector as an input and uses some more parameters to plot histograms.

Syntax

使用 R 创建直方图的基本语法为：

The basic syntax for creating a histogram using R is −

hist(v,main,xlab,xlim,ylim,breaks,col,border)

以下是所用参数的描述 -

Following is the description of the parameters used −

  1. v is a vector containing numeric values used in histogram.

  2. main indicates title of the chart.

  3. col is used to set color of the bars.

  4. border is used to set border color of each bar.

  5. xlab is used to give description of x-axis.

  6. xlim is used to specify the range of values on the x-axis.

  7. ylim is used to specify the range of values on the y-axis.

  8. breaks is used to mention the width of each bar.

Example

使用 input 向量、标签、col 和边框参数创建简单的直方图。

A simple histogram is created using input vector, label, col and border parameters.

下方给出的脚本将在当前 R 工作目录中创建并保存直方图。

The script given below will create and save the histogram in the current R working directory.

# Create data for the graph.
v <-  c(9,13,21,8,36,22,12,41,31,33,19)

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

# Create the histogram.
hist(v,xlab = "Weight",col = "yellow",border = "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 −

histogram

Range of X and Y values

若要指定 X 轴和 Y 轴允许的值范围，我们可以使用 xlim 和 ylim 参数。

To specify the range of values allowed in X axis and Y axis, we can use the xlim and ylim parameters.

每个条形的宽度可以通过 breaks 决定。

The width of each of the bar can be decided by using breaks.

# Create data for the graph.
v <- c(9,13,21,8,36,22,12,41,31,33,19)

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

# Create the histogram.
hist(v,xlab = "Weight",col = "green",border = "red", xlim = c(0,40), ylim = c(0,5),
   breaks = 5)

# 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 −

histogram lim breaks