I need to construct a confusion matrix in R$.$ Tried a lot of options and still having an errorError in $"[.$data.frame" $($heart$\_$data, c$("$age$",$ "talach", $"$cp$",$ "trestbps"$))$: undefined columns selected

Traceback:

heart$\_$data$[$c$("$age$",$ "talach", $"$cp$",$ "trestbps"$)]$

$\text{'}[.$data.frame" $($heart$\_$data, c$("$age$",$ "talach", $"$cp$",$ "trestbps"$))$

stop$("$undefined columns selected"$)$