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Re^5: filtering an array

by philiprbrenan (Monk)
on Sep 01, 2012 at 23:03 UTC ( #991211=note: print w/replies, xml ) Need Help??


in reply to Re^4: filtering an array
in thread filtering an array

Likewise, the for is unnecessary in this code too:

for (@positions) {@positions = map $_->[0], @positions;}

It should just be:

@positions = map $_->[0], @positions;

because map iterates over the array you give it. Even better, you could write:

$_ = $_->[0] for @positions;

here we are making the for implicit in map explicit.

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Re^6: filtering an array
by prbndr (Acolyte) on Sep 01, 2012 at 23:15 UTC

    perl still has a problem with this:

    @positions = grep $_->[1] =~ /ac/i, @positions;

    with the same error Use of uninitialized value in pattern match (m//)

      One or more of the elements of the array @positions is undefined. The easiest way to check this is like this:

      use Data::Dump qw(pp); pp([@positions]);

      This will give you a printout of the value of each element in array @positions. I expect we will see that some are "undef" meaning undefined. It will be these elements that are causing the problem.

        i don't see any that are "undef. that's a little strange. the data dumper output prints:

        9031,

        "A"

        etc. etc. this is a little strange...

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[shmem]: well finally.
[stevieb]: nice! I just finished a GPS "take me home" device last week, and did a bunch of software updates to it yesterday. I also created a pseudo chip with an Arduino to simulate an IC, where it responds to register read/writes over the I2C bus...
[stevieb]: ...from an I2C master. It's ugly and there are many changes I'm going to make, but I had not done anything like it before. It's designed for my RPi:: automated test platform; a system that does CI on *all* my RPi modules.
[shmem]: pseudo chip?
[stevieb]: well, what happens is the Arduino 'listens' for requests r/w, and does the appropriate thing when it's interrupted based on the 'register' address sent in. It's ugly as it was my first attempt, but I've got great new ideas I'm just sitting.
[stevieb]: ...down to implement now. Here's the sketch as it currently sits
[shmem]: well I use I2C and SPI and stuff, but creating a pseudo chip looks to me like lot of indirection and memory clutter... not?

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