使用固定的r2模拟逻辑回归的数据

I would like to simulate data for a logistic regression where I can specify its explained variance beforehand. Have a look at the code below. I simulate four independent variables and specify that each logit coefficient should be of size log(2)=0.69. This works nicely, the explained variance (I report Cox & Snell's r2) is 0.34. I would like to simulate data for a logistic re