Flip array index with sed - sed

Question

I have some java code declaring a 2d array that I want to flip.
Content is like:
zData[0][0] = 198;
zData[0][1] = 198;
zData[0][2] = 198;
...
And I want to flip indices to have
zData[0][0] = 198;
zData[1][0] = 198;
zData[2][0] = 198;
So I tried doing it with sed:
sed -r 's#zData[([0-9]*)][([0-9]*)]#zData[\2][\1]#g' DataSample1.java
But unfortunately sed says:
sed: -e expression #1, char 43: Unmatched ) or \)
Might the string "zData" hold kind of flag or option?
I tried not using the -r option but I have the same kind of message for:
sed 's#zData[\(\[\0\-\9\]\*\)][\(\[\0\-\9\]\*\)]#zData[\2][\1]#g' DataSample1.java
Thanks for your help

Answer 1

Simples:
$ sed -r 's/(zData)(\[[^]]+])(\[[^]]+])/\1\3\2/' file
zData[0][0] = 198;
zData[1][0] = 198;
zData[2][0] = 198;
Regexplanation:
# Match
(zData) # Capture the variable name we want to transpose
( # Start capture group for first index
\[ # Opening bracket escaped to mean literal [
[^]]+ # One or more none ] characters i.e the digits
] # The closing literal ] doesn't need escaping here.
) # Close the capture
(\[[^]]+]) # Same regexp as before for the second index
# Replace
\1\3\2 # Switch the indexes but rearranging the 2nd and 3rd capture groups
Note: Switch \[[^]]+] to if it is clearer \[[0-9]+] for you, so instead of saying match an opening square bracket followed by one or more none-closing brackets followed by a closing bracket you are saying match an opening square bracket followed by one or more digit followed by a closing bracket.

Answer 2

Try that one:
sed 's#\([a-zA-Z0-9_-]\+\)\(\[[^]]*\]\)\(\[[^]*]\]\)\(.*$\)#\1\3\2\4#'
It adds four captures for the variable name, the first index, the second index and the rest and then switches order.
Edit: #Sudo_O's solution with extended regular expressions is much more readable. Thx for that! Nevertheless, on some systems sed -r may not be available, since it is not part of basic POSIX.