Indexing to create a new array

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Kate
Kate 2013-11-11
评论： Marc 2013-11-12
I have a very simple question, but just can't seem to wrap my brain around the answer today.
My index:
>> Wtr
Wtr =
12
1
2
My data:
mNEE =
1.0000 NaN
2.0000 NaN
3.0000 0.2165
4.0000 3.9982
5.0000 18.3253
6.0000 32.6099
7.0000 14.7678
8.0000 36.8627
9.0000 -1.0730
10.0000 -8.2807
11.0000 6.7998
12.0000 25.0182
1.0000 8.1078
2.0000 0.7304
3.0000 -6.2877
4.0000 -2.5207
5.0000 10.5052
6.0000 11.2116
7.0000 4.8839
8.0000 -8.1560
9.0000 -16.8618
10.0000 -45.3915
11.0000 -39.8423
12.0000 -8.4954
1.0000 13.1454
2.0000 31.7136
3.0000 41.5338
4.0000 19.9113
5.0000 18.7724
6.0000 -20.1884
7.0000 -7.9781
8.0000 -12.7571
9.0000 -21.3081
10.0000 -18.9930
11.0000 -31.7573
12.0000 -7.2601
1.0000 10.2586
2.0000 16.4023
3.0000 45.1588
4.0000 24.6945
5.0000 0.0275
6.0000 7.3914
7.0000 -3.5258
8.0000 -15.4096
9.0000 -19.4229
10.0000 -21.2903
11.0000 -11.5092
12.0000 -55.0183
1.0000 -53.4840
2.0000 -4.5846
3.0000 14.0066
4.0000 0.5472
5.0000 31.4220
6.0000 8.1386
7.0000 -13.0516
8.0000 -2.7136
9.0000 NaN
10.0000 NaN
11.0000 NaN
12.0000 NaN
All that I really want to do is pull data where the 1st column of mNEE==Anything in Wtr.
But when I run this super simple for loop I only get the first 3 matches, when I want all the data that falls within the category of Wtr in a new array:
for i=1:length(mNEE)
t=mNEE(Wtr,:);
end
>> t
t =
12.0000 25.0182
1.0000 NaN
2.0000 NaN
Could someone please help me understand why Matlab finds the first 3 matches, but not anymore? This seems so simple but is eluding me.
Thanks a million.

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采纳的回答

Image Analyst
Image Analyst 2013-11-11
Try this:
matchingRows = ismember(mNEE(:,1), Wtr)
extractedRows = mNEE(matchingRows, :)
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Kate
Kate 2013-11-11
And I checked to see if my Matlab was getting cranky, but it can find simple ismembers:
test =
1
2
3
4
5
6
7
8
9
10
>> t=[2,4,6]'
t =
2
4
6
>> ismember(test, t)
ans =
0
1
0
1
0
1
0
0
0
0
Kate
Kate 2013-11-11
Nevermind, this works perfectly, thanks :)

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更多回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-11-11
编辑：Azzi Abdelmalek 2013-11-11
mNEE =[1.0000 NaN
2.0000 NaN
3.0000 0.2165
4.0000 3.9982
5.0000 18.3253
6.0000 32.6099]
wtr=[12;1;2]
idx=ismember(mNEE(:,1),wtr)
mNEE(idx,:)=[]
%or
data=mNEE(~idx,:)
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Marc
Marc 2013-11-12
Just that you are RIGHT and Kate is WRONG.... Let it begin

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