Could not import PIL.Image even if Pillow already installed?

问题

I'm going through chapter 5 of the book Deep Learning with R (https://livebook.manning.com/book/deep-learning-with-r/chapter-5/112).

When running the code below, the following error appears: Error in py_iter_next(it, completed) : ImportError: Could not import PIL.Image. The use of load_img requires PIL.

All answers with regard to this error message recommend using pip install pillow. When I run this in my Terminal, the following appears:

Requirement already satisfied: pillow in /anaconda3/lib/python3.7/site-packages (6.1.0)

Hence, Pillow is already installed, whereas I cannot run the code below. I'm working with a Mac Book Pro platform x86_64-apple-darwin15.6.0 as well as R version 3.6.0 (2019-04-26). I also have Python 3.7.3 installed on my machine. Any referrals and support are highly appreciated!

#Displaying a batch of data and labels
batch <- generator_next(train_generator)
str(batch)

回答1:

The problem is that Keras for R creates its own virtual environment, called r-reticulate, and pillow is missing in there. You also have to find out whether it used conda or virtualenv to create such environment. Then, activate it and install pillow and scipy. Finally, restart the R session.

In my case it was conda:

$ conda env list
# conda environments:
#
base                  *  C:\Users\black\Anaconda3
py2                      C:\Users\black\Anaconda3\envs\py2
r-reticulate             C:\Users\black\Anaconda3\envs\r-reticulate

$ conda activate r-reticulate
$ conda install pillow scipy

来源：https://stackoverflow.com/questions/57612703/could-not-import-pil-image-even-if-pillow-already-installed