take the measure of (someone or something)
To evaluate someone or something; to judge the qualities of someone or something. Every year I have an informal day of classes so I have a chance to take the measure of my kids.
get/have/take the ˈmeasure of somebody
, get/have/take somebody’s ˈmeasure
(formal) form an opinion about somebody’s character or abilities so that you can deal with them: The champion soon had the measure of his young opponent.