If you do not want to drive, it is possible to get to Yosemite Valley by train or bus. You can take the train from San Francisco to Merced (six hours), and from there take the bus to the National Park.
In San Francisco area you will also find many agencies that organize bus tours to the Yosemite National Park. Some of them include only transportation, and others offer guided tours of the park.
♥ Visit Tagulandang Island ♥