consistent usages of `np.RandomState` in the code

[wyli]

1. There are some usages of np.random.* in the transforms (see below). ..

./monai/transforms/signal/array.py:276:np.random.choice
./monai/transforms/signal/array.py:357:np.random.choice
./monai/transforms/spatial/array.py:1214:np.random.randint
./monai/transforms/spatial/dictionary.py:2347:np.random.randint
./monai/transforms/spatial/dictionary.py:698:np.random.randint
./monai/transforms/utils.py:1220:np.random.random
./monai/transforms/utils.py:246:np.random.randint
./monai/transforms/utils.py:510:np.random.randint
./monai/transforms/utils.py:552:np.random.random
./monai/transforms/utils.py:607:np.random.random

2. There are some usages in other parts of the main code. Same question on what to do with those remains:

./monai/apps/deepedit/interaction.py:65:np.random.choice
./monai/apps/deepedit/transforms.py:159:np.random.choice
./monai/apps/deepedit/transforms.py:60:np.random.choice
./monai/apps/detection/transforms/dictionary.py:1305:np.random.randint
./monai/apps/nuclick/transforms.py:370:np.random.choice
./monai/apps/nuclick/transforms.py:377:np.random.choice
./monai/auto3dseg/analyzer.py:190:np.random.rand
./monai/auto3dseg/analyzer.py:191:np.random.rand
./monai/auto3dseg/analyzer.py:292:np.random.rand
./monai/auto3dseg/analyzer.py:374:np.random.rand
./monai/auto3dseg/analyzer.py:862:np.random.rand
./monai/auto3dseg/operations.py:119:np.random.rand
./monai/auto3dseg/operations.py:120:np.random.rand
./monai/auto3dseg/operations.py:121:np.random.rand
./monai/auto3dseg/operations.py:122:np.random.rand
./monai/auto3dseg/operations.py:62:np.random.rand
./monai/data/synthetic.py:142:np.random.random
./monai/data/synthetic.py:65:np.random.random
./monai/data/utils.py:125:np.random.randint
./monai/utils/misc.py:353:np.random.seed
./monai/visualize/utils.py:92:np.random.rand
./monai/visualize/utils.py:97:np.random.rand

3. What to do with usage of np.random.* in tests/**/*.py files? Numpy states that:

New code should use the normal method of a Generator instance instead; please see the Quick Start.

So it seems like there is no need to migrate those immediately, but just wanted to mention that here. Since there are around ~390 usages in tests I am not listing them here.

I found usages using the following bash command: find . -name "*.py" -exec grep -o -H -n -E 'np.random.\w+' {} \; | grep -v "RandomState" | sort | uniq

Originally posted by @john-zielke-snkeos in #6854 (comment)

[wyli]

(cc @ericspod @john-zielke-snkeos follow-up of the discussions in #6854, self.R and RandomState is currently preferred over np.random.*, this ticket is to track the issue.
e.g. preferred usage:

MONAI/monai/data/synthetic.py

Line 65 in 8aabdc9

rs: np.random.RandomState = np.random.random.__self__ if random_state is None else random_state # type: ignore

)

[ericspod]

If we wanted to first change the usages of np.random.* to use a RandomState then migrate in the future to Generator we could do the following:

• Change the usage of np.random.* in transforms to use self.R. This will change some expected deterministic behaviour but would be more reproducible.
• In other places in core change routines to accept a RandomState object as an argument and use that, defaulting to np.random if none is provided. This would cover most use cases with minimal addition. @wyli 's code snippet is probably the technique to use for this.
• In apps/* and auto3dseg ask contributors what they would want to do, mentioning we're trying to tighten up the implementation with an eye to future migration.

We do need to have a more considered discussion about what to do about migration at some point, either we move to Generator or we do implement our own class to replace RandomState usage.