热图着色依赖于值高于或低于零

I am trying to make a heatmap in R where my data ranges from -5 to +50. I would like values of 0 to be white, the values between 0 and -5 to be coloured on a gradient from white to blue and the values between 0 and +50 to be coloured from white to red. Ideally, I'd also like the same scaling to be used, i.e. the darkness of blue at -5 to be the same as the darkness of the red at +5. I am trying to make a heatmap in R where my dat