See the image below.
Work Step by Step
To graph the following function, we will first determine its parent function and then stretch the whole graph step by step. The parent function of $y=|cos(\pi x)|$ is $y=cosx$ (Black dotted line graph in the image). Now, lets transform it a little and graph: $y=cos(\pi x)$, which means shrinking the parent graph horizontally by the factor of $\pi$ (Red line graph in the image) Finally, we graph: $y=|cos(\pi x)|$, which means that we will reflect the portion of the graph below the x-axis about the x-axis (Blue line graph in the image).