How to apply conditional statements so as to select certain rows or columns on a given dataset.

Question

Manduna Watson 2014-7-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/140056-how-to-apply-conditional-statements-so-as-to-select-certain-rows-or-columns-on-a-given-dataset

评论： Manduna Watson 2014-7-21

How do I apply conditional statements so as to select certain rows or columns on a given dataset (like the one below)? For example, I would like to (1) display records with r only , (2) count records with + only .

Please note that the example of the data to be analyzed is given below. The data is separated by space. The data has 12 columns whose headings are; Event, time, from_Node, to_Node, Packet_Type, Packet_Size, Flags, Fid, Source_Address, Destination_Address, Sequence_Number and Packet_Id .

For example, + 0.155355 1 3 tcp 1500 ------- 0 0.0 3.0 2 3;

+ is an event,

0.155355 is time in secs,

1 is from_Node,

3 is to_Node,

tcp is Packet_Type, 1500 is Packet_Size,

------- are Flags,

0 is Fid,

0.0 is Source_Address,

3.0 is Destination_Address,

2 is Sequence_Number and

3 is Packet_Id.

_ _This is the data _

+ 0.155355 1 3 tcp 1500 ------- 0 0.0 3.0 2 3

- 0.160955 1 3 tcp 1500 ------- 0 0.0 3.0 2 3

r 0.170955 1 3 tcp 1500 ------- 0 0.0 3.0 1 2

r 0.178955 1 3 tcp 1500 ------- 0 0.0 3.0 2 3

+ 0.203632 1 3 tcp 1500 ------- 0 0.0 3.0 3 6

- 0.203632 1 3 tcp 1500 ------- 0 0.0 3.0 3 6

+ 0.206032 1 3 tcp 1500 ------- 0 0.0 3.0 4 7

+ 0.211632 1 3 tcp 1500 ------- 0 0.0 3.0 5 8

Thank you

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Manduna Watson 2014-7-4

This works. Thank you very much.

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Answer 1

Cedric 2014-7-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/140056-how-to-apply-conditional-statements-so-as-to-select-certain-rows-or-columns-on-a-given-dataset#answer_143533

编辑：Cedric 2014-7-4

在 MATLAB Online 中打开

Here is another approach

 content = fileread( 'myData.txt' ) ;
 nPlus   = sum( content == '+' ) ;
 rRows   = regexp( content, '(?<=(^|\n)r )[^\r\n]*', 'match' ) ;

with that you get

 >> nPlus
 nPlus =
         4

and

 >> fprintf( '%s\n', rRows{:} ) ;
    0.170955 1 3 tcp 1500 ------- 0 0.0 3.0 1 2
    0.178955 1 3 tcp 1500 ------- 0 0.0 3.0 2 3

PS: I can explain the regexp pattern if anyone is interested. Just let me know.

EDIT: I slightly modified the call to regexp to manage cases with/without header.

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Cedric 2014-7-3

编辑：Cedric 2014-7-3

The pattern matches the following

as many characters as possible which are different from \r and |

Manduna Watson 2014-7-21

Using the same technique, how can I, for example,

(A): select and display data with + , 3 , and tcp only .

(B): select and add data with + , 3 , tcp and 3.0 only

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Answer 2

Sara 2014-7-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/140056-how-to-apply-conditional-statements-so-as-to-select-certain-rows-or-columns-on-a-given-dataset#answer_143532

在 MATLAB Online 中打开

clc
clearvars
% Read file
filecontent = cell(1000,1);
k = 0;
fid = fopen('mydata.txt','r');
while 1
    t = fgetl(fid);
    if(~ischar(t)),break,end
    k = k + 1;
    filecontent{k} = t;
end
filecontent = filecontent(1:k);
fclose(fid);
% To get only the first character
fid = fopen('mydata.txt','r');
t = textscan(fid,'%s%*[^\n]');t = t{1};
fclose(fid);
% r data
index_r = find(strcmp(t,'r')==1);
filecontent(index_r)
% + data
index_plus = find(strcmp(t,'+')==1);
numel(index_plus)