仅在存在零和零的情况下才从数组中切除零 [英] Cut off leading and trailing zeros from array, only if they exist

问题描述

我正在尝试截取可能包含或不包含它们的输入数组的前导零和/或尾随零.我已经看到了以下问题的答案:

I am trying to cut off the leading and/or trailing zeros of an input array that may or may not have them. I have seen the answers to questions like:

MATLAB-删除向量中的前导零和尾随零

在我的输入数组实际上不以零开始/结束之前，这一直很好:

And this works fine until my input array doesn't actually start/end with zeros:

input = [ 1 2 0 3 4 0 0 0 0 ]

如果这是我的输入数组，则上述问题的答案将切断我所需的值.

If this was my input array, the answer to the above question would cut off values that I need.

在无法保证前导零位/尾随零位时，是否有一种简洁的方法(即没有长的"if"语句)?

Is there a succinct way (i.e. no long 'if' statements) to remove leading/trailing zeros, when there is no guarantee that they will be there?

为澄清起见进行

我知道我可以使用find()函数获取非零索引数组，然后执行以下操作:

I know that I can use the find() function to get an array of nonzero indexes, and then do something like:

indexes = find(input)
trimmed_input = input( indexes(1):indexes(end) )

但是出现一个问题，因为我不能保证输入数组将具有尾随/前导零，并且可能(可能会)在非零值之间具有零.所以我的输入数组可能是以下之一:

But a problem arises, because I have no guarantee that the input array will have trailing/leading zeros, and may (probably will) have zeros in between nonzero values. So my input array could be one of:

input1 = [ 0 0 0 nonzero 0 nonzero 0 0 0 ]  =>  [ nonzero 0 nonzero ]
input2 = [ nonzero 0 nonzero 0 0 0 ]  =>  [ nonzero 0 nonzero ]
input3 = [ 0 0 0 nonzero 0 nonzero ]  =>  [ nonzero 0 nonzero ]

input4 = [ 0 0 0 nonzero nonzero 0 0 0 ]  =>  [ nonzero nonzero ]
input5 = [ 0 0 0 nonzero nonzero ]  => [ nonzero nonzero ]
input6 = [ nonzero nonzero 0 0 0 ]  => [ nonzero nonzero ]

使用上述方法，在input2或input3上将修剪我要保留的值.

And using the method above, on either input2 or input3 will trim values that I want to keep.

推荐答案

我现在可以想到一种简单的方法来完成它，但是我认为这应该可行:

I can think of neat way to do it one-liner at the moment, but i think this should work:

if input(1)==0
    start = min(find(input~=0))
else
    start = 1;
end
if input(end)==0
    endnew = max(find(input~=0))
else
    endnew = length(input);
end
trimmed_input = input(start:endnew);

• 如果它以0开头，则需要找到第一个非零元素.
• 如果它以0结尾，则需要找到最后一个非零元素.

编辑

哈，找到了一根衬里:)

Ha, found the one liner :)

trimmed_input = input(find(input~=0,1,'first'):find(input~=0,1,'last'));

不知道这实际上是快速的还是不太复杂.

No idea of if this is actually fast or is less complex.

另一种选择(理解@jrbedard的意思):

Another alternative (understood what @jrbedard meant):

trimmed_input = input(min(find(input~=0)):max(find(input~=0)));

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