read data from delimited text file
显示 更早的评论
Hi,
I have a delimited text file that contains 8 rows and 4 columns and this is repeated for 'n' sets. I need to copy the 4th column value of each rows and make a new variable.
There will be a total of 8 variables with dimension (n,1).
I can use dlm read to read the file. But I am having trouble creating nested loops to achieve the goal.
I have attached the text file for reference. What would be the best way to tackle the problem ?
采纳的回答
Star Strider
2021-1-12
This is one of the more difficult files I have managed to import!
See if this does what you want:
fidi = fopen('water.txt');
for k = 1:3
hdr{k,:} = fgets(fidi); % Read & Store Header Lines
end
k1 = 1;
while ~feof(fidi)
sechdr(k1,:) = textscan(fidi, '%f%f',1);
if isempty(sechdr)
break
else
for k2 = 1:8
secline(k2,:) = textscan(fidi, '%f%f%f%f%f',1);
end
secdata{k1} = cell2mat(secline);
k1 = k1+1;
end
end
fclose(fidi);
with:
hdr_1 = sechdr(1,:) % Display Data (Delete)
data_1 = secdata{1}
hdr_LastFull = sechdr(k1-2,:) % Display Data (Delete)
data_LastFull = secdata{k1-2}
producing:
hdr_1 =
1×2 cell array
{[5000]} {[8]}
data_1 =
1.0000e+00 1.6087e-07 2.0500e-01 8.4682e-02 2.8968e-01
2.0000e+00 5.3421e-02 1.0823e-01 1.0074e-02 1.7172e-01
3.0000e+00 3.7223e-02 1.2488e-02 2.2847e-02 7.2557e-02
4.0000e+00 2.0605e-01 2.9866e-02 1.9402e-01 4.2994e-01
5.0000e+00 1.4819e-01 4.3587e-02 5.9918e-02 2.5170e-01
6.0000e+00 6.4602e-02 1.2636e-01 1.2115e-02 2.0308e-01
7.0000e+00 3.7825e-01 2.5960e-01 1.9181e-01 8.2967e-01
8.0000e+00 1.1831e-02 3.4485e-02 3.8945e-02 8.5260e-02
hdr_3219 =
1×2 cell array
{[3223000]} {[8]}
data_3219 =
1.0000e+00 6.1856e-05 2.4395e+01 1.8241e+01 4.2636e+01
2.0000e+00 5.7546e+00 4.7172e+01 1.0499e+01 6.3425e+01
3.0000e+00 9.7735e+00 4.3917e+01 3.9653e+01 9.3343e+01
4.0000e+00 2.5318e+00 3.9988e+01 3.5174e+00 4.6038e+01
5.0000e+00 7.7347e+00 1.4633e+01 6.8984e+00 2.9266e+01
6.0000e+00 5.2029e+00 3.6422e+01 8.2238e+01 1.2386e+02
7.0000e+00 3.1026e+01 1.0219e+01 3.8708e-02 4.1284e+01
8.0000e+00 2.0353e-01 3.2281e+00 8.1987e+00 1.1630e+01
The ‘hdr’ cell array are the first 3 header lines in the file. The ‘sechdr’ cell array are the first row of each section, and ’secdata’ are the matrix following it.
.
6 个评论
Tejas Appaji
2021-1-12
Star Strider
2021-1-12
As always, my pleasure!
If you do not need the first three header lines in ‘hdr’, just ignore them. That loop must be kept in my code however in order for the rest of the code to work. If you do not need the ‘sechdr’ values, just ignore them as well. That line however must also be kept in my code for my code to work.
The cat function apparently does not want to concatenate these, so a loop is the only option:
for k = 1:k1-2
secdata3(:,:,k) = cell2mat(secdata(k));
end
That produces a (8x5x3219) array.
To extract only column 5 from ‘secdata3’:
Column5 = squeeze(secdata3(:,5,:));
produces a (8x3219) double matrix, consisting of only column 5 from each ‘secdata’ matrix. (The squeeze function eliminates the singleton dimension.)
If you only want the first row of the last column, that would be:
Row1_Column5 = Column5(1,:);
producing a (1x3219) vector.
.
Tejas Appaji
2021-1-12
Star Strider
2021-1-12
As always, my pleasure!
This was definitely an interesting problem!
Tejas Appaji
2021-1-12
Star Strider
2021-1-12
Thank you!
I also continue to learn from Answers others post here, since MATLAB is such a large universe.
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Environment and Settings 的更多信息
产品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
