How to calculate the 'Coefficient of determination' for a linear model in R?

Use summary(model) to print a point by point yield into de reassurance. You can likewise utilize str to investigate the structure of an item, for instance str(summary(model)) this is valuable when you can to extricate some portion of that yield utilizing $.

result <- summary(model) # summary of the model

str(result) # see structure of the summary

result$r.squared

Result contains both, R.squared and Adjusted R squared, see for example the following output

Residual standard error: 0.09178 on 148 degrees of freedom

Multiple R-squared: 0.9643,

Adjusted R-squared: 0.964

F-statistic: 3992 on 1 and 148 DF

p-value: < 2>

Output is just the last part of summary(model) printed in the console