chart

Graphs and charts provide a visual representation of the data. They provide a clearer and quicker understanding of the impact of certain statistics. Thus, SUSI.AI Android app makes use of bar charts to display statistics related to user ratings for SUSI skills. This blog guides through the steps to create a Horizontal Bar Chart, using MPAndroidChart library, that has been used in the SUSI.AI Android app skill details page to display the five star skill rating by the users. On vertical axis : Labels of the rating shown On horizontal axis : Percentage of total number of users who rated the skill with the corresponding number of stars on the vertical axis Step - 1 : Add the required dependencies to your build.gradle. (a) Project level build.gradle allprojects { repositories { maven { url 'https://jitpack.io' } } } (b) App level build.gradle dependencies { implementation 'com.github.PhilJay:MPAndroidChart:v3.0.3' }   Step - 2 : Create an XML layout. <?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <!-- Add a Horizontal Bar Chart using MPAndroidChart library --> <com.github.mikephil.charting.charts.HorizontalBarChart android:id="@+id/skill_rating_chart" android:layout_width="match_parent" android:layout_height="match_parent" /> </android.support.constraint.ConstraintLayout>   Step - 3 : Create an Activity and initialize the Horizontal Bar Chart. class MainActivity : Activity { lateinit var skillRatingChart : HorizontalBarChart override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.chart) setSkillGraph( ) } }   Step - 4 : Create a method in your MainActivity to set up the basic properties and the axes. /** * Set up the axes along with other necessary details for the horizontal bar chart. */ fun setSkillGraph(){ skillRatingChart = skill_rating_chart //skill_rating_chart is the id of the XML layout skillRatingChart.setDrawBarShadow(false) val description = Description() description.text = "" skillRatingChart.description = description skillRatingChart.legend.setEnabled(false) skillRatingChart.setPinchZoom(false) skillRatingChart.setDrawValueAboveBar(false) //Display the axis on the left (contains the labels 1*, 2* and so on) val xAxis = skillRatingChart.getXAxis() xAxis.setDrawGridLines(false) xAxis.setPosition(XAxis.XAxisPosition.BOTTOM) xAxis.setEnabled(true) xAxis.setDrawAxisLine(false) val yLeft = skillRatingChart.axisLeft //Set the minimum and maximum bar lengths as per the values that they represent yLeft.axisMaximum = 100f yLeft.axisMinimum = 0f yLeft.isEnabled = false //Set label count to 5 as we are displaying 5 star rating xAxis.setLabelCount(5) //Now add the labels to be added on the vertical axis val values = arrayOf("1 *", "2 *", "3 *", "4 *", "5 *") xAxis.valueFormatter = XAxisValueFormatter(values) val yRight = skillRatingChart.axisRight yRight.setDrawAxisLine(true) yRight.setDrawGridLines(false) yRight.isEnabled = false //Set bar entries and add necessary formatting setGraphData() //Add animation to the graph skillRatingChart.animateY(2000) } Here is the XAxisValueFormatter class that is used to add the custom labels to the vertical axis : public class XAxisValueFormatter implements IAxisValueFormatter { private String[] values; public XAxisValueFormatter(String[] values) { this.values = values; } @Override public String getFormattedValue(float value, AxisBase axis) { // "value" represents the position of the label on the axis (x or y) return this.values[(int) value]; } }   Step - 5 : Set the bar entries. /** * Set the bar entries i.e. the percentage of users who rated the skill with * a certain number of stars. * * Set the colors for different bars and the bar width of the bars. */ private fun…