2. After the Advance

Pie Charts

A pie chart is a circular chart that is divided into circular slices to show proportions and percentages in each category as part of the whole or total value. They are extensively used in business presentations and educations to compare the proportions in different categories, for e.g. population division of an area, etc. However, pie charts are not advisable if there are more categories or large amounts of data as the size of the slice becomes smaller and is difficult to decipher the results and analysis from them. In this article, we will discuss Pie Chart in MATLAB in detail.

Types of Pie Chart in MATLAB

Below are the types of Pie Chart in MATLAB.

1. Pie(X)

In MATLAB we can draw pie chart by using pie(X) function represented by the values present in X, each slice or proportion in the chart represents a part of X. If the data type of X is categorical then the slices in chart are shown by the respective categories, the area of each category or slice in the chart is determined by the number of values in the category divided by number of values in X. If X is number then the values in X must be finite. If the input array is in numbers then by default the output is in terms of percentage and the respective colors.

There are many operations that can be performed using pie(X) such as:

  • pie(X, labels): This is used to label the slices in the chart and the number of labels should be equal to the number of the values present in X which should be finite and numeric.
  • pie(X, explode): explode is a matrix of zeroes and non-zeroes that represents the value if X. This function is used to explode or separate the slices from the chart. If explode is categorical then it can be an array of category names, any string array, the numeric or logical vector that represents each category present in X and pie separate the slices according to the categories in explode. If the explode is numerical then it should be a matrix of zeroes and non-zeroes or a numerical vector that represents the value of X. explode should be of the same size as of X.
  • pie(X, explode, labels): This function is used to explore and label the categories for each slice in X. If X is numerical then the number of labels should be equal to the number of elements in X and if X is categorical then the number of labels should be equal to the number of categories present in X.
  • pie(ax,..) and pie(..) are some of the functions, where ax value plots the output the specified value given.

2. Pie3(X)

This function in MATLAB is used to create a three-dimensional pie chart representing the data present in X. The values in X can be represented as a slice or as part of the total value.

There are many operations which can be performed using this function which is almost same as the operations used in pie(X) function like:

  • pie3(X, labels): This function is used to label the slices according to the categories present in X and the number of labels for each slice should be the same as the number of categories in X.
  • pie3(X, explode): This function is used to explode or separate the slice from the center of the chart.
  • pie3(axes_handle,..): This function plots the output in the axes as specified by the “axes_handle” keyword instead of the current axes.
  • pie3(…): This function returns text graphics object or a vector of handles to patch.

Advantages and Disadvantages of Pie Charts

Following are the advantages and disadvantages:

Advantages of Pie Charts

  • Pie charts are easy to read charts to the uninformed audiences, which represents the data as a fractional part of the whole and it makes the readers or viewers compare various categories and draw conclusions effectively at a glance.
  • They are present in many statistical softwares like R, SPSS, Excel, etc. which is easy to interpret and do not require any additional explanation while visualizing the data.
  • It enables the readability of the data as we can manipulate or change the slices in the pie chart to emphasize the points that we want to show to the readers as part of the business objective. Pie charts are visually simpler than any other charts like bar charts, histograms, etc.

Disadvantages of Pie Charts

  • Pie charts are not suitable for large data sets. If the number of categories in the dataset is more than the number of slices in the chart will be more and it increases the complexity to read the proportions and make the analysis.
  • The pie chart does not reveal the actual values of the data like small quantities or decimals may not be easily represented. Data Manipulation of the charts can lead the readers to draw incorrect conclusions based on the visual impact rather than the data analysis. They do not help us in understanding the reasons or any key assumptions.
  • Pie charts are not preferred while dealing with the data having similar values because when we divide the data into slices, the similarity in the data makes the readers difficult to compare between categories and diversity between them is not properly conveyed. They take up more space as compared to other alternatives in the data visualization.

Some of the alternatives to the pie chart which can overcome the above disadvantages are bar charts, histogram, and Doughnut charts. Doughnut charts share the same circular shape and functionality of the pie chart but add the benefit to display the data from multiple data sets which is not possible in the simple pie chart.

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