how to import a file in MATLAB?

Question

Jesus 2013-10-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/88995-how-to-import-a-file-in-matlab

回答： Gautam PAL 2013-10-16

采纳的回答： Nishitha Ayyalapu

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I want to import a file (.dat or txt) in MATLAB, which contains numbers and NaN in some columns.

My file looks like this:

Name: 
Day: 5/07/21998
    UT      LT    hpp  fpH  SSP  EF   GG 
0808  21.0808  227  -    -  N
1732  21.1732  300  4.7  340  -  N
2533  21.2533  237  4.6  335  -  N
3333  21.3333  249  -    -  N
4233  21.4233  251  -    -  N
5033  21.5033  244  4.6  328  -  N
5833  21.5833  256  -    -  N
6733  21.6733  253  4.7  330  -  N

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Walter Roberson 2013-10-3

Do any values before the UT heading need to be imported? Which of the columns do you want read in? For example the EF column is shown here as always "-", but should that be skipped or read in? In the SSF column, should the blank entries be important as 0 or as NaN or should the column be imported as string without numeric interpretation?

Jesus 2013-10-3

编辑：Jesus 2013-10-3

1- No. The data before UT does not need to be imported.

2- I'd like to read all the columns (UT, LT, hpp, fph, SSP, EF, GG). UT( float), LT (float), hpp(float), fpH(float), SSP(float), EF(string or char), GG (string or char).

Note: each column is separated by tab

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Answer 1

Nishitha Ayyalapu 2013-10-14

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https://ww2.mathworks.cn/matlabcentral/answers/88995-how-to-import-a-file-in-matlab#answer_99665

编辑：Nishitha Ayyalapu 2013-10-14

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You could use

readtable

Lets say your data is in testdata.txt then following would create a table "T" with 7 columns, 8 rows and also saves column headers (UT, LT, hpp..etc).

to access UT column you would do

T.UT

However, with this approach fpH to hold all numeric data as float, the '-' entries are treated as empty and are recorded as nan.

   T = readtable('testdata.txt','Delimiter','\t','HeaderLines',3,...
                    'TreatAsEmpty','-','Format','%f%f%f%f%f%s%s');

If fpH has to hold '-' entries and also the numeric data, fpH can be read as a string. But all the numeric data is also recorded as string

T = readtable('testdata.txt','Delimiter','\t','HeaderLines',3,...
                    'Format','%f%f%f%s%f%s%s');

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Walter Roberson 2013-10-15

编辑：Walter Roberson 2013-10-15

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readtable() is very new. You can convert Nishitha's code as:

fid = fopen('testdata.txt', 'r');
T = textscan(fid, '%f%f%f%f%f%s%s', 'Delimiter','\t','HeaderLines',3,...
                  'TreatAsEmpty','-');
fclose(fid);