stepwise regression: Undefined function ' stepwiselm' for input arguments of type 'cell' - matlab

I have one .txt file and I have converted it to first a table Ta(Ta=readtable（'xxx.txt'）) then an array Aa（Aa=table2array(Ta)）, the .txt file contains 220 rows and 12 cols, but the table and the array only have 219 rows and 1 col. Where did I do wrong?
Then when I tried to do stepwise regression I got error message: Undefined function ' stepwiselm' for input arguments of type 'cell'.
My coad was: mdl=stepwiselm(Aa)
In the .txt file, the first raw are texts e.g. elevation, hight, yields etc. I though I could use these names to define Predictor variables and Response variable. But since these names are lost in Aa, how should I write code for stepwise regression?Thanks!


Try the following
delim = ' ';
nrhdr = 1;
A = importdata('A-100spreg2-raa06a.txt', delim, nrhdr);
A.data will be your data, A.textdata your header. A ".txt" does not contain columns, so you need to specify a delimiter (I assumed a space). You can then use your A.data in your stepwise function.
As you indicated you wanted column 10 as y, and I assume others as X, use
stepwise(A.data(:,1:9),A.data(:,10))
I wouldn't use the headers for anything other than creating labels in figures.

Related

How to load a csv file as a datamatrix in matlab?

I try to load a csv file in matlab to use a certain column as a vector for a OLS estimation. However, my csv looks like:
Date KCFSI
13 2004-02-01 -0.67
14 2004-03-01 -0.58
15 2004-04-01 -0.57
16 2004-05-01 -0.49
17 2004-06-01 -0.67
...
and I want to have the the column KCFSI as a vector.
I tried:
x=fopen('kcfsi.csv');
kcfsi=x(:,2);
But I don't even get a matrix for my x. Just get as value : "14" for whatever reason. I want to have something like "2x100"

csvread cannot open csv files containing non-Numeric values as stated in the documentation.
The file must contain only numeric values.
So you should use textscan as explained in this answer : https://stackoverflow.com/a/19613301/11756186
Alternatively you can use the readtable built-in function
csvtable = readtable('kcfsi.csv');
kcfsi_array = csvtable.KCFSI; %Column vector with the content of the KCFSI column

fopen returns a fileID, not a matrix.
Use A = readmatrix(filename) or M = csvread(filename) instead.

Problems reading a .csv file with ezread

I was trying to read a csv file with ezread https://de.mathworks.com/matlabcentral/fileexchange/11026-ezread and I get the following problem:
Error using textscan
The second input must be a format character vector containing at least one >specifier or a literal field.
Error in ezread (line 66)
data = textscan(fid,format_str,'delimiter',file_delim,'headerlines',1);
I call the function as follows:
tmpName = '/path/file.csv';
structRead = ezread(tmpName, 'r');
I have checked if tmpName is correct with isfile(), so it is a correct path.
First two rows of my file have the following format:
a,b,c,d
1,2,e,f
Do you know where the problem could be ?

Instead ezread, you should use importdata. However it will not recognize separation on comma ,. So you need to add extra line:
tmpName = importdata('/path/file.csv');
structRead = split(a, ',')
The result is:
2×4 cell array
{'a'} {'b'} {'c'} {'d'}
{'1'} {'2'} {'e'} {'f'}

How do I read comma separated values from a .txt file in MATLAB using textscan()?

I have a .txt file with rows consisting of three elements, a word and two numbers, separated by commas.
For example:
a,142,5
aa,3,0
abb,5,0
ability,3,0
about,2,0
I want to read the file and put the words in one variable, the first numbers in another, and the second numbers in another but I am having trouble with textscan.
This is what I have so far:
File = [LOCAL_DIR 'filetoread.txt'];
FID_File = fopen(File,'r');
[words,var1,var2] = textscan(File,'%s %f %f','Delimiter',',');
fclose(FID_File);
I can't seem to figure out how to use a delimiter with textscan.

horchler is indeed correct. You first need to open up the file with fopen which provides a file ID / pointer to the actual file. You'd then use this with textscan. Also, you really only need one output variable because each "column" will be placed as a separate column in a cell array once you use textscan. You also need to specify the delimiter to be the , character because that's what is being used to separate between columns. This is done by using the Delimiter option in textscan and you specify the , character as the delimiter character. You'd then close the file after you're done using fclose.
As such, you just do this:
File = [LOCAL_DIR 'filetoread.txt'];
f = fopen(File, 'r');
C = textscan(f, '%s%f%f', 'Delimiter', ',');
fclose(f);
Take note that the formatting string has no spaces because the delimiter flag will take care of that work. Don't add any spaces. C will contain a cell array of columns. Now if you want to split up the columns into separate variables, just access the right cells:
names = C{1};
num1 = C{2};
num2 = C{3};
These are what the variables look like now by putting the text you provided in your post to a file called filetoread.txt:
>> names
names =
'a'
'aa'
'abb'
'ability'
'about'
>> num1
num1 =
142
3
5
3
2
>> num2
num2 =
5
0
0
0
0
Take note that names is a cell array of names, so accessing the right name is done by simply doing n = names{ii}; where ii is the name you want to access. You'd access the values in the other two variables using the normal indexing notation (i.e. n = num1(ii); or n = num2(ii);).

Using fscanf in MATLAB to read an unknown number of columns

I want to use fscanf for reading a text file containing 4 rows with an unknown number of columns. The newline is represented by two consecutive spaces.
It was suggested that I pass : as the sizeA parameter but it doesn't work.
How can I read in my data?
update: The file format is
String1 String2 String3
10 20 30
a b c
1 2 3
I have to fill 4 arrays, one for each row.

See if this will work for your application.
fid1=fopen('test.txt');
i=1;
check=0;
while check~=1
str=fscanf(fid1,'%s',1);
if strcmp(str,'')~=1;
string(i)={str};
end
i=i+1;
check=strcmp(str,'');
end
fclose(fid1);
X=reshape(string,[],4);
ar1=X(:,1)
ar2=X(:,2)
ar3=X(:,3)
ar4=X(:,4)
Once you have 'ar1','ar2','ar3','ar4' you can parse them however you want.

I have found a solution, i don't know if it is the only one but it works fine:
A=fscanf(fid,'%[^\n] *\n')
B=sscanf(A,'%c ')
Z=fscanf(fid,'%[^\n] *\n')
C=sscanf(Z,'%d')
....

You could use
rawText = getl(fid);
lines = regexp(thisLine,' ','split);
tokens = {};
for ix = 1:numel(lines)
tokens{end+1} = regexp(lines{ix},' ','split'};
end
This will give you a cell array of strings having the row and column shape or your original data.
To read an arbitrary line of text then break it up according the the formating information you have available. My example uses a single space character.
This uses regular expressions to define the separator. Regular expressions powerful but too complex to describe here. See the MATLAB help for regexp and regular expressions.

Import csv file in Matlab

I need your help to import some csv files into matlab. They have the following format
#CONTENT
Class,Category,Level,Form
xxxxx,xxxxx,1.0,1
#DATA_GENERATION
Date,Agency,Version,ScientificAuthority
2010-04-08,INME,1.0,XXX xxx xxxx
#PLATFORM
Type,ID,Name,Country,GAW_ID
STN,308,xxxx,xxx
#INSTRUMENT
Name,Model,Number
ECC,6A,6A23500
#LOCATION
Latitude,Longitude,Height
25,-3,631.0
#TIMESTAMP
UTCOffset,Date,Time
+00:00:00,2010-04-07,10:51:00
* SOFTWARE: SNDPRO 1.321
* TROPOPAUSE IN MB 184
*
#FLIGHT_SUMMARY
IntegratedO3,CorrectionCode,SondeTotalO3,CorrectionFactor,TotalO3,WLCode,ObsType,Instrument,Number
328.4,0,379.9
#AUXILIARY_DATA
MeteoSonde,ib1,ib2,PumpRate,BackgroundCorr,SampleTemperatureType,MinutesGroundO3
RS92-SGPW,,,,Pressure,Pump
#PUMP_CORRECTION
Pressure,Correction
2.0,1.171
3.0,1.131
5.0,1.092
10.0,1.055
20.0,1.032
30.0,1.022
50.0,1.015
100.0,1.011
200.0,1.008
300.0,1.006
500.0,1.004
1000.0,1.000
#PROFILE
Pressure,O3PartialPressure,Temperature,WindSpeed,WindDirection,LevelCode,Duration,GPHeight,RelativeHumidity,SampleTemperature
945.36,4.590,14.6,10.0,30,2,0,631,43,22.8
944.90,4.620,14.3,7.8,20,0,2,635,44,22.8
943.51,4.630,13.9,7.6,17,0,4,647,44,22.8
942.13,4.620,13.4,8.1,16,0,6,660,45,22.8
940.98,4.590,13.0,9.0,16,0,8,670,45,22.8
939.83,4.590,12.6,9.8,17,0,10,680,46,22.8
938.69,4.600,12.1,10.3,18,2,12,691,46,22.8
937.77,4.600,12.2,10.9,18,0,14,699,47,22.9
936.63,4.600,12.1,11.4,19,0,16,709,47,22.9
935.48,4.600,11.8,11.9,19,0,18,719,47,22.9
934.12,4.600,11.7,12.3,19,0,20,731,47,22.9
932.98,4.590,11.6,12.6,19,0,22,742,48,22.9
931.84,4.590,11.6,12.9,18,0,24,752,48,22.9
930.93,4.600,11.6,13.2,18,0,26,760,48,22.9
929.79,4.600,11.4,13.4,17,0,28,770,49,22.9
928.88,4.610,11.5,13.6,16,0,30,778,49,22.9
927.98,4.620,11.4,13.7,15,0,32,787,49,23.0
927.30,4.620,11.3,13.8,14,0,34,793,49,23.0
The first line of the file is empty and second line contains the #CONTENT. I would like to have in a matrix all data that are under the line Pressure,O3PartialPressure,Temperature,WindSpeed,WindDirection,LevelCode,Duration,GPHeight,RelativeHumidity,SampleTemperature

Use the csvread() function. From the documentation:
csvread Read a comma separated value file.
M = csvread('FILENAME') reads a comma separated value formatted file
FILENAME. The result is returned in M. The file can only contain
numeric values.
In your case, since you want to exclude all of the content up until the #PROFILE data, you would have to know the line number of the data you're interested in in advance, then use one of the following uses (again from the documentation):
M = csvread('FILENAME',R,C) reads data from the comma separated value
formatted file starting at row R and column C. R and C are zero-
based so that R=0 and C=0 specifies the first value in the file.
M = csvread('FILENAME',R,C,RNG) reads only the range specified
by RNG = [R1 C1 R2 C2] where (R1,C1) is the upper-left corner of
the data to be read and (R2,C2) is the lower-right corner. RNG
can also be specified using spreadsheet notation as in RNG = 'A1..B7'.