ggcoxfunctional
(Package: survminer) :
Functional Form of Continuous Variable in Cox Proportional Hazards Model
Displays graphs of continuous explanatory variable against martingale residuals of null cox proportional hazards model, for each term in of the right side of formula. This might help to properly choose the functional form of continuous variable in cox model (coxph). Fitted lines with lowess function should be linear to satisfy cox proportional hazards model assumptions.
providing 
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