在Matlab中加快循环 [英] Speed up for loop in Matlab
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问题描述
对于循环,我有以下,这使得我的程序在文件大小非常大时运行非常慢。
我从PLY文件中读取 data
作为这里使用命令 data = textread(fileName,'%s','delimiter ','\\\
。
'); data
是一个* 1单元格数组。 data
中的每个元素都是一个char值为7 * 1的单元数组。示例数据文件是此处。
< (数据)-1
pc(i,1)=(str2double(cellstr(data {i,1}){1,1})pre>
));
pc(i,2)=(str2double(cellstr(data {i,1} {2,1})));
pc(i,3)=(str2double(cellstr(data {i,1} {3,1})));
pc(i,4)=(str2double(cellstr(data {i,1} {4,1})));
pc(i,5)=(str2double(cellstr(data {i,1} {5,1})));
pc(i,6)=(str2double(cellstr(data {i,1} {6,1})));
end
解决方案
>> pc = str2double([data {:}]。')
pc =
0.1033 -0.2737 0.8570 221.0000 196.0000 174.0000 255.0000
0.1054 -0.2731 0.8550 220.0000 195.0000 173.0000 255.0000
...
0.1139 -0.2803 0.8490 221.0000 194.0000 172.0000 255.0000
0.1117 -0.2829 0.8500 225.0000 200.0000 178.0000 255.0000
您可以使用
>>来移除最后一列和最后一行(就像您的问题中所做的那样) pc = pc(1:end-1,1:end-1)
pc =
0.1033 -0.2737 0.8570 221.0000 196.0000 174.0000
0.1054 -0.2731 0.8550 220.0000 195.0000 173.0000
.. 。
0.1139 -0.2803 0.8490 221.0000 194.0000 172.0000
I have the following for
loop which makes my program runs very slow when the file size is very big. What is the best way to vectorize it.
I read data
from a PLY file as here using the command, data = textread(fileName, '%s','delimiter', '\n');
.data
is a n*1 cell array. Each element in data
is a 7*1 cell array of char values. Sample data file is here.
for i = 1:length(data)-1
pc(i, 1) = (str2double(cellstr(data{i,1}{1,1})));
pc(i, 2) = (str2double(cellstr(data{i,1}{2,1})));
pc(i, 3) = (str2double(cellstr(data{i,1}{3,1})));
pc(i, 4) = (str2double(cellstr(data{i,1}{4,1})));
pc(i, 5) = (str2double(cellstr(data{i,1}{5,1})));
pc(i, 6) = (str2double(cellstr(data{i,1}{6,1})));
end
解决方案
This will do what you want
>> pc = str2double([data{:}].')
pc =
0.1033 -0.2737 0.8570 221.0000 196.0000 174.0000 255.0000
0.1054 -0.2731 0.8550 220.0000 195.0000 173.0000 255.0000
...
0.1139 -0.2803 0.8490 221.0000 194.0000 172.0000 255.0000
0.1117 -0.2829 0.8500 225.0000 200.0000 178.0000 255.0000
You can remove the last column and row (as appears to be done in your question) with
>> pc = pc(1:end-1, 1:end-1)
pc =
0.1033 -0.2737 0.8570 221.0000 196.0000 174.0000
0.1054 -0.2731 0.8550 220.0000 195.0000 173.0000
...
0.1139 -0.2803 0.8490 221.0000 194.0000 172.0000
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