Individual skill usage subsections in SUSI Skill CMS

In SUSI.AI Skills CMS several interactive skill related statistics are displayed on the skill page for each skill which includes user ratings, ratings over time, user feedback and skill usage data displayed interactively. The skill usage section is further subdivided to get more insight into how the skill has been used and from where. Therefore we have three subsections which display Time wise skill usage, device wise usage, and country wise usage. All this data can help evaluate which devices are mostly using the skill or data like in which country the skill is more popular than others. So in this post, we mainly discuss the UI of how these sections are implemented.


Adding a Card component to the skill page component at the bottom of the skill page component.



In the render function of the newly made component, we import the Paper component from material-ui and render it at the top to contain the subsections to give it a card-like UI.

   <Paper className="margin-b-md margin-t-md">


Create div for the time wise skill usage. Calculate total skill usage for displaying the total skill usage count and also it helps to decide whether we need to render the section or not. So if the total skill usage by time count is greater than zero then render the line chart for visual analysis and display the total skill usage count too.

let totalSkillUsage = 0;
if (this.props.skill_usage) {
 // eslint-disable-next-line
 totalSkillUsage = this.props.skill_usage.reduce((totalCount, day) => {
        if (day) {
         return totalCount + day.count;
        return totalCount;
 }, 0);

<div className="time-chart">
        <ResponsiveContainer width={this.state.width} height={300}>
           <XAxis dataKey="date" padding={{ right: 20 }} />
           <YAxis allowDecimals={false} />
           <Tooltip wrapperStyle={{ height: '60px' }} />
           <Legend />
<div className="total-hits">
 <div className="large-text">{totalSkillUsage}</div>
 Hits this week


Create div for the Device wise usage. Conditionally render it in case the device wise data is available in the props.

<div className="device-usage">
 <div className="sub-title">Device wise Usage</div>
 {this.props.device_usage_data &&
 this.props.device_usage_data.length ? (
        <div className="pie-chart">
         <ResponsiveContainer width={600} height={350}>
               {, index) => (
                 <Cell key={index} fill={entry.color} />
             <Legend wrapperStyle={{ position: 'relative' }} />


Create a div for the country wise usage. We get the country wise usage data from the props and then we plug in the data in the geo chart component and also display the data as a table on the side. In case no data comes in or is unavailable we do not render the component at all.

 {countryWiseSkillUsage && countryWiseSkillUsage.length ? (
        <div className="country-usage-container">
         <div className="country-usage-graph">
           <GeoChart data={countryWiseSkillUsage} />
         <div className="country-usage-list">
 ) : (
        <div className="unavailable-message">
         Country wise usage distribution is not available.


This is how the three subsection in the skill usage component are implemented


Implementing a skill rating over time graph section in SUSI Skill CMS

In SUSI.AI skill ratings is an invaluable aspect which greatly helps the users to know which skills are performing better than the rest and are more popular than the others. A robust skill rating system for the skills was developed recently which allows the users to rate skills as per their experience and thus data like average rating, total number of ratings is available but there was no provision to see the rating history or how the skills rating has changed over time, this could be an important aspect for users or developers to know what changes to the skill made it less/more popular. An API is developed at the server to retrieve the ratings over time data, we can use these details to render attractive components for a better visual understanding of how the skill is performing and get statistics like how the skill’s rating has changed over time.

About the API

Endpoint : /cms/getRatingsOverTime.json


  • model
  • group
  • language
  • skill

After consuming these params the API will return the number of times a skill is called along with

the date on which it is called. We use that data as an input for the line chart component that we want to render. 

Fetching data from the server and storing in the application state

Make an AJAX call to the server to fetch the data from the URL which holds the server endpoint, on successfully receiving the data we do some formatting with the timestamp that comes along the data to make it more convenient to understand and then we call a saveRatingOverTime function which saves the data received from the server to the application state.

let ratingOverTimeUrl = `${urls.API_URL}/cms/getRatingsOverTime.json`;
skillUsageUrl = skillUsageUrl + '?model=' + modelValue + '&group=' + this.groupValue + '&language=' + this.languageValue + '&skill=' +;
// Fetch the skill ratings over time
 url: ratingOverTimeUrl,
 dataType: 'json',
 crossDomain: true,
 success: function(data) {
        if (data.ratings_over_time) {
         const ratingData = => {
             return {
               rating: item.rating,
               count: item.count,
               timestamp: parseDate(item.timestamp)
                 .split(' ')
                 .slice(2, 4)
                 .join(' '),
 error: function(e) {


Save the skill usage details in the component state.

// Save ratings over time data in the component state
saveRatingOverTime = (ratings_over_time = []) => {


Send the received data as props to the Skill Rating component and render it.

<SkillUsageCard skill_usage={this.state.skill_usage} /> 

Implementing the UI

Importing the packages for rendering the chart in the Skill Ratings component.

import { XAxis, YAxis, Tooltip, LineChart, Line, Legend, ResponsiveContainer } from 'recharts';


Display a small heading for the section in the ratings card and Render a Responsive container component which will form a parent component for out Chart which will be rendered when the ratings over time data received in the props is not empty.

<div className="sub-title" style={{ alignSelf: 'flex-start' }}>
 Rating over time
{this.props.ratings_over_time.length ? (
           window.innerWidth < 660
             ? this.state.width
             : this.state.width * 1.5
) : (
 <div>No ratings data over time is present</div>


Render a LineChart and supply data from the data prop received from the Skill Listing component, add X-Axis and Y-Axis by supplying corresponding dataKey props depending on the data received, Add a tooltip to describe points on the line chart and a legend which describes the lines, After that we have a Line component which depicts the change in ratings over time on the chart.

        top: 5,
        right: 30,
        left: 20,
        bottom: 5,
 <XAxis dataKey="timestamp" padding={{ right: 20 }} />
 <YAxis dataKey="rating" />
 <Tooltip wrapperStyle={{ height: '60px' }} />
 <Legend />
        name="Average rating"
        activeDot={{ r: 8 }}


So I hope after going through this blog it is more clear how the ratings over time section is implemented in the Skill CMS.



Characteristization of Transistors Using PSLab

Transistors are one of the key building blocks of all electronics. They are fundamentally three-terminal semiconductor devices, with the terminals being labelled as the Emitter(E), Base(B), and Collector(C). These active components are found everywhere in electronics, and all of the complex processors that power everything from cellphones to aircraft employ millions of these devices in switching and amplification roles. In this blog post, we shall use the PSLab to explore some of the fundamental properties of transistors, and their various applications.

Transistor as an amplifier

In the schematic shown, we shall try to use an NPN transistor to amplify a small signal.

A small amplitude oscillation generated by W1 with the amplitude knob turned down to a very low level is used as the input. Since transistors do not handle bipolar signals, we have mixed a constant DC voltage generated PV3 to shift this small signal into the positive domain.

The fluctuating potential difference incident at the base of the transistor creates a corresponding current flow between the Base and Emitter.

By the fundamental property of transistors, this influences the path resistance between the Collector(C) and the Emitter(E) , and the resultant amplified voltage output can be monitored at the junction between the 1K resistor and the collector.

We have used CH1 to monitor the input voltage, and CH2 for the output

In a more applied scenario, we can implement the second schematic in order to create an audio amplifier. Instead of using W1 as the input signal, a speaker is used as a microphone. When a sound signal is incident on the speaker, its membrane oscillates, and as a result , the coil attached to it also does the same. Since this coil is placed in a magnetic field , its oscillations result in a change in the magnetic flux passing through, and this change causes a voltage(EMF) induced at its output. We then use our transistor amplifier to amplify this small EMF

Figure 2 : A Transistor being used to apply a gain of 81.5x to a small amplitude sine wave. The input waveform (green) is shown on a +/-500mV full scale and the output waveform is shown on a +/-8V scale in order to be able to view both. However, due to the difference in scales, the actual difference in amplitudes is 16 times more than what is visible.
Common Emitter Characteristics
Schematic Diagram

Any introductory course on transistors includes a diagram similar to the one shown , and a description about how for any base current, the collector current eventually saturates, and that this saturation level is proportional to the base current itself.

With the PSLab’s transistor CE characterization app, we can set up this experiment, and verify this for ourselves using an NPN transistor. The results shown were gathered using a 2N2222 transistor

In the schematic , the base current is determined by the voltage source PV2, and a high value series resistor of 200 KOhms . We use an analog input CH3 to monitor the voltage present at the Base of the transistor in order to calculate the total base current.

Base current = V/R = (PV2 – CH3) / 200e3

Now that we have set a particular base current, PV1 is used to sequentially increase the voltage across the collector and emitter of the transistor. A current limiting resistor of 1K Ohm is used, and CH1 is used to monitor the voltage drop across the transistor.

Collector current = V/R = (PV1 – CH1) / 1e3

Plotting the behaviour of the collector current with respect to the collector voltage gives us the familiar current voltage characteristics of a transistor.

Figure 3: Common emitter characteristics of an NPN transistor (2N2222) for various base currents

We can now alter the base current by changing PV2, and verify that the saturation current for the collector is indeed a function of it.