London attack Twitter tears analysed in Oz

Europe was blanketed in sadness following the London terror attack, according to an Australian analytics tool monitoring emotional expression on Twitter across the globe.

We Feel, built by CSIRO subset Data61, processes up to 45,000 tweets per minute to determine the various sentiments felt in each state and country in near real-time.

British-born Khalid Masood on Wednesday mowed down multiple people in a car on London's Westminster bridge, killing three and injuring scores more, before stabbing a police officer to death.

Masood was later shot dead.

We Feel logged the impact of the attack as it reverberated across Europe.

Senior principal researcher at Data61, Dr Cecile Paris, says sadness hit a monthly peak.

"We conjecture this is what happened," she told AAP on Friday.

"In Europe, for sadness, there has certainly been a peak in response to the attack."

A total of 397,363 tweets processed by the tool within 24 hours contained words associated with sadness.

This was up by more than 80,000 on the previous day, and the second-highest peak of sadness expressed on Twitter in Europe in 2017.

"When I was monitoring the Charlie Hebdo terrorist attack in Paris, again I could see some more negative emotion coming out there," Dr Paris said.

"We also did see a situation around the Sydney siege."

The researcher said Twitter provides access to one per cent of public posts on its application and We Feel searches for expressive and reactionary tweets using a list of 500 "emotional" words.

"We're querying with words like sad, happy, angry, annoyed, ashamed," she said.

We Feel then sorts them into categories: love, joy, surprise, fear, anger, sadness and other.

It showed a "statistically significant" peak of sadness worldwide when actor Robin Williams died in 2014, while there was "some joy" felt in Australia when Malcolm Turnbull won the federal election, Dr Paris said.

Data gathered by the tool is publicly available and aims to assist mental health workers with intervention plans.