Histograms in R | R Tutorial 2.4 | MarinStatsLectures

MarinStatsLectures-R Programming & Statistics
9 Aug 201304:40
EducationalLearning
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TLDRIn this instructional video, Mike Marin guides viewers on creating histograms in R to analyze numeric data distributions, using lung capacity data as an example. He explains how to customize histograms by changing y-axis representation from frequencies to probability density, adjusting bin width, and setting axis limits. Additionally, he demonstrates adding a density curve with customizable color and line width, and encourages further exploration of R's plotting capabilities.

Takeaways
  • 📊 The video is about producing histograms in R for summarizing numeric variable distributions.
  • 🔍 Histograms are generated using the 'hist' command in R, with the default setting reporting frequencies.
  • 📈 To change the y-axis to represent 'probability density' instead of 'frequencies', set 'freq' to FALSE or 'prob' to TRUE.
  • 👀 R recognizes 'FALSE' with a capital 'F' and 'TRUE' with a capital 'T' for boolean arguments.
  • 📐 The 'xlim' and 'ylim' arguments can be used to change the limits of the x and y axes respectively.
  • 🗂 The 'breaks' argument allows customization of bin width by specifying the number of breakpoints or the actual breakpoints.
  • 🔢 Using 'sequence', one can define a series of breakpoints for the histogram bins.
  • 🏷️ Titles and axis labels can be added using the 'main', 'xlab', and 'ylab' arguments.
  • 🔄 The 'las' argument can be set to 1 to rotate the y-axis labels for better readability.
  • 📈 A 'density curve' can be added to the histogram using the 'lines' command for a visual representation of the distribution.
  • 🎨 The appearance of the density curve can be customized with the 'col' for color and 'lwd' for line width.
  • 💡 For further customization and plot refinement, the Help menu in R is a valuable resource, and more will be discussed in subsequent videos.
Q & A

  • What is the main topic of the video presented by Mike Marin?

    -The main topic of the video is producing histograms using R to summarize the distribution of a numeric variable.

  • Which data set is used in the video for demonstrating histogram creation?

    -The lung capacity data set is used for demonstrating how to create histograms in R.

  • What is the default output of a histogram in R in terms of y-axis representation?

    -By default, R reports 'frequencies' on the y-axis of a histogram.

  • How can the y-axis of a histogram be changed to represent 'probability density' instead of 'frequencies'?

    -To change the y-axis to represent 'probability density', set the 'freq' argument to FALSE or use the 'prob' argument and set it to TRUE.

  • What are the two ways to indicate a FALSE value for an argument in R?

    -In R, you can indicate a FALSE value for an argument by using 'FALSE' or simply 'F'.

  • How can the limits of the x or y-axis be adjusted in a histogram?

    -The limits of the x or y-axis can be adjusted using the 'xlim' or 'ylim' arguments in the histogram function.

  • What does the 'breaks' argument in the 'hist' command allow you to do?

    -The 'breaks' argument allows you to specify the number of breakpoints or the exact breakpoints for the bins in a histogram.

  • How many bins will be produced if you set the 'breaks' argument to 7?

    -Setting the 'breaks' argument to 7 will result in 8 bins being produced.

  • What command can be used to create a sequence of breakpoints for the 'breaks' argument?

    -The 'sequence' command can be used to create a sequence of breakpoints for the 'breaks' argument.

  • How can you add a title and labels to the axes of a histogram in R?

    -A title can be added using the 'main' argument, and axis labels can be added using the 'xlab' and 'ylab' arguments.

  • What command and arguments are used to overlay a density curve on a histogram in R?

    -The 'lines' command is used to overlay a density curve, and you can change the color using the 'col' argument and the width using the 'lwd' argument.

  • How can you rotate the values on the y-axis of a histogram?

    -You can rotate the values on the y-axis by setting the 'las' argument equal to 1.

  • What does the video suggest for further learning about refining plots in R?

    -The video suggests exploring the Help menu and watching later videos in the series for further insights on refining plots and making them more aesthetically pleasing.

Outlines
00:00
📊 Introduction to Histograms in R

In this video, Mike Marin introduces the concept of creating histograms to summarize the distribution of a numeric variable using R. He uses the lung capacity data set as an example, which has been previously introduced. The video begins with the basic 'hist' command in R to produce a histogram for the variable 'LungCap', showing the default settings like frequencies, title, and bin width. Mike explains how to customize the histogram by changing the y-axis to represent a 'probability density' instead of 'frequencies', using the 'freq' or 'prob' arguments. He also covers how to adjust the x and y limits with 'xlim' and 'ylim', and how to modify the bin width using the 'breaks' argument. Additionally, he discusses adding a title with 'main', labeling axes with 'xlab' and 'ylab', and rotating y-axis values with the 'las' argument.

Mindmap
Keywords
💡Histogram
A histogram is a graphical representation used to show the distribution of a numeric variable. In the context of the video, histograms are produced to summarize the distribution of lung capacity data. The script mentions using the 'hist' command in R to generate a histogram, which is central to the video's theme of data visualization.
💡Lung Capacity (LungCap)
Lung Capacity, denoted as 'LungCap' in the script, refers to the total volume of air that the lungs can hold. It is the numeric variable for which the distribution is being analyzed in the video. The script discusses producing a histogram for this specific variable to understand its distribution within the dataset.
💡Frequencies
Frequencies in the context of histograms represent the number of data points that fall within each bin or range of values. The video script explains that R's default setting for histograms reports frequencies, which is a fundamental concept for understanding the basic output of a histogram.
💡Probability Density
Probability density is a concept used to describe the relative likelihood of a continuous variable taking on a particular value. The script discusses changing the y-axis from frequencies to a probability density function by setting the 'freq' argument to FALSE, which is crucial for understanding the distribution in a probabilistic sense rather than a simple count.
💡Bin Width
Bin width refers to the range of values that each bar in the histogram represents. The script explains how to change the bin width using the 'breaks' argument in R, which is an important aspect of customizing a histogram to better visualize the data distribution.
💡Break Points
Break points are the specific values that define the boundaries of the bins in a histogram. The script mentions specifying the number of break points or the exact values for these points, which is essential for controlling the granularity of the histogram's bins.
💡xlim and ylim
The 'xlim' and 'ylim' arguments in R are used to set the limits for the x and y axes of a plot, respectively. The script uses these arguments to adjust the viewable range of the histogram, which helps in focusing the viewer's attention on specific parts of the data distribution.
💡Sequence
The 'sequence' command in R is used to generate a sequence of numbers. In the script, it is mentioned as a way to specify custom breakpoints for the histogram bins, which allows for more precise control over the histogram's structure.
💡Main, xlab, ylab
These are arguments in R used to add titles and labels to a plot. 'main' is for the overall title, 'xlab' for the x-axis label, and 'ylab' for the y-axis label. The script discusses using these to enhance the readability and interpretability of the histogram.
💡Density Curve
A density curve is a smoothed version of a histogram that provides a clearer picture of the distribution's shape. The script describes adding a density curve to the histogram using the 'lines' command in R, which is an advanced technique for visualizing the data distribution.
💡las
The 'las' argument in R is used to control the orientation of axis labels. The script mentions setting 'las' to 1 to rotate the y-axis labels, which is a design choice to improve the presentation and readability of the histogram.
Highlights

Introduction to producing histograms in R for summarizing numeric variable distributions.

Using the 'hist' command in R to create a histogram for the Lung Capacity (LungCap) variable.

Understanding R's default settings for histograms: frequencies, title, and bin width.

Changing the y-axis to represent 'probability density' instead of 'frequencies' using the 'freq' argument.

Using 'F' to set the 'freq' argument to FALSE for probability density in histograms.

Altering the histogram's x or y limits with the 'xlim' or 'ylim' arguments.

Adjusting bin width in histograms using the 'breaks' argument with a specified number of breakpoints.

Specifying custom breakpoints for histogram bins using the 'breaks' argument.

Utilizing the 'sequence' command to set custom bin ranges in histograms.

Adding a title to the histogram with the 'main' argument.

Labeling the x-axis and y-axis with 'xlab' and 'ylab' arguments.

Rotating y-axis labels using the 'las' argument set to 1.

Overlaying a density curve on the histogram with the 'lines' command.

Customizing the density curve's color with the 'col' argument.

Adjusting the line width of the density curve using the 'lwd' argument.

Encouragement to explore the Help menu in R for further customization of plots.

Promise of future videos on refining plots and enhancing their aesthetic appeal.

Transcripts

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HistogramsR ProgrammingData VisualizationLung CapacityProbability DensityFreq ArgumentBin WidthDensity CurvePlot CustomizationStatistical AnalysisR Tutorial