How to use readtable when skipping every second (non-data) line?
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Sjoukje de Lange
am 9 Mai 2022
Bearbeitet: Sjoukje de Lange
am 10 Mai 2022
Hi all,
I'm trying to load a file using readtable - see attached snip. The file has 314 colums and many rows. Every second row consists of actual data (e.g. line 10, 12, 14...) and the other rows are headerlines (lines <8) or non-data (e.g. line 9, 11, 13...). How can I read this file so it skips all the non-data lines?
I know how to skip headerlines: data = readtable ('file.dat', 'NumHeaderLines', 10);
But I don't know how to skip every second line. I've been trying to play around with detectImportOptions en setvaropts, but so far (very) unsuccesful. Help! :)
6 Kommentare
dpb
am 9 Mai 2022
This is an abomination -- how was this file created; no chance of fixing it on creation I suppose?
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Mathieu NOE
am 9 Mai 2022
hello
try this
T = readtable ('samplefile.txt', 'NumHeaderLines', 8,"Delimiter",' ');
[m,n] = size(T);
select_rows = 1:2:m;
TT = T(select_rows,:)
2 Kommentare
Mathieu NOE
am 10 Mai 2022
hello
can you share the entire file and tell us which data is to be retrieved (important) and what can be left behind ?
dpb
am 9 Mai 2022
>> C=readcell('samplefile.txt');
>> C=C(9:2:end,:);
>> C(1:12,:)
ans =
12×3 cell array
{[16]} {[26]} {'52.7 1900 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'52.7 1900 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'52.9 1902 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.0 1904 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.1 1906 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.2 1908 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.3 1910 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.4 1912 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.6 1914 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.7 1916 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.8 1918 200 450→→ RGC→154→0…'}
{[16]} {[26]} {'53.9 1920 200 450→→ RGC→154→0…'}
>> strlength(C(1,3))
ans =
2199
>> sum(C{1,3}==9)
ans =
618
>> D=split(C(1,3));
>> whos D
Name Size Bytes Class Attributes
D 314x1 35256 cell
>> D=str2double(split(C(1,3)));
>> whos D
Name Size Bytes Class Attributes
D 314x1 2512 double
>> D(1:20)
ans =
52.7
1900
200
450
NaN
154
0
0
0
0
0
0
0
0
464.2
459.9
456.5
453.7
450.7
447.8
>> sum(isfinite(D))
ans =
313
>> C{1,3}(1:50)
ans =
'52.7 1900 200 450 RGC 154 0.0'
>>
Do you know how many variables are in each file a priori, somehow?
The multiple tabs really screw things up although it looks like maybe can deal with it.
I've not had much direct success with in import options object although with enough time/effort it can undoubtedly be done.
I might just resort to the old "one at a time" here with fgetl and split(), though, and be done with it.
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