alternatively you can create a multi staged build.

also you dont need clean up the builder, since the unused files are not used in the final image.

also add a new file you can just append it to the builder. (not rebuild required of the previous installs required since you don't care about the size of the builder image )

  FROM python:3.8-alpine as builder
  
  RUN apk add --virtual build-dependencies gcc build-base freetype-dev libpng-dev openblas-dev
  RUN pip install matplotlib pandas

  FROM python:3.8-alpine
  # a couple of copy commands to copy binaries and py files from builder to the final image. 
  COPY --from=builder /usr/bin /usr/bin
  COPY --from=builder /usr/local/lib/ /usr/local/lib/