Emojis portray Joburg's negativity
South Africa's economic hub Johannesburg is among the saddest cities in the world.
This is according to a new tool that tracks the most used emojis on micro-blogging site Twitter across the world.
Emoji Cities, created by Smart Destinations, uses Twitter data to map happiness across the globe.
It shows which cities are laughing or crying, which are sleepy and which are blowing kisses, by listing the most popular emojis, hashtags, tweets, trends and other information for each.
The data is updated every day to show changes in sentiment and feeling, ranking the top emojis and most positive cities on a global scale.
By also showing what is being talked about in each city, listing the top five trending hashtags and the five most commonly tagged accounts, people can see just how widely subjects are discussed by the world.
The data is sourced from 69 cities around the world using the official Twitter application programming interface.
Emoji Cities examines what the world is talking about. Using Twitter activity, it finds out which celebrities are trending, what topics are in the news, and the most popular tweets in every major city, as well as the most popular emoji being used.
For the positivity rating, each tweet is analysed for its sentiment, positive or negative. The positivity score is calculated as the percentage of positive tweets out of all tweets with sentiment (neutral tweets are not counted).
According to the data, Quito in Ecuador; Chennai, India; and Dakar, Senegal are the most positive cities, all ranked at 78%, while the average worldwide positive ranking is 72%.
On the flip side, Philadelphia, Washington DC (both US cities) and Johannesburg are the most negative cities, all sitting at 71%.
According to the data, the top 10 emojis are face with tears of joy, loudly crying face, red heart, rolling on the floor laughing, smiling face with heart eyes, fire, weary face, smiling face with smiling eyes, purple heart and female sign, respectively.
Commenting on the findings, Dr Wasim Ahmed, lecturer in digital business at Northumbria University, says: "The role that Twitter now plays in how word spreads around the world means that some news stories can develop at an astonishing rate, sometimes faster than they do through the media.
"Combined with a lack of the fact-checking processes that news organisations use before running a story, this means reactions and emotions to events can become particularly polarised, regardless of whether the story is accurate or not.
"All of this means that sentiments in various cities can change extremely quickly. Looking at the data from Twitter worldwide gives a near accurate real-time insight into public sentiment and mood in a way that has never been possible before.
"By examining differences in mood across the world in this way, it is fascinating to see how the effects of events on the ground take hold."