Taking slices with tensorA

I've set up a simple tensor with indices 'a' and 'b'.

ftable(B)

  b           u           v           w           x           y
a
a1   0.001868954 0.403345197 0.030088185 0.137252368 0.142634612
a2   0.396935972 0.945219795 0.068828465 0.314180585 0.446338719
a3   0.752412200 0.748810918 0.125532631 0.471686930 0.345062348
a4   0.191103000 0.536607533 0.257740399 0.525900194 0.976841803
a5   0.581585362 0.679024312 0.333035405 0.460748770 0.438562927

Now I try two ways of taking the subtensor with index 'b'=2:

B[a=1:5, b=2]

[1] 0.4033452 0.9452198 0.7488109 0.5366075 0.6790243
attr(,"class")
[1] "tensor"

B[b=2, a=1:5]

[1] 0.39693597 0.94521979 0.06882847 0.31418058 0.44633872
attr(,"class")
[1] "tensor"

This does not seem consistent with the spirit of having named indices whose
order does not matter.

Now, what I *really* want to do is take the subtensor where 'b' has the name
'u' or 'w' (for instance)...

Any suggestions?

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