Problems with empty cell in a large matrix
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Poulomi Ganguli
le 20 Mar 2019
Commenté : Peter Perkins
le 30 Août 2019
Hello:
I have a large matrix of 102730 rows in the form of text file (sample text file is attached) with some header files in it. The first column show year, the next the month, followed by the day, and value1, value2 and value 3. Some of the cells are missing/empty. I want to fill these empty cells with NaN, so that they don't interefere with the next value. I am also attaching the text files of sample input (sample.txt) and desired output (Output.txt) for your reference.
Could anyone please let me know how to retrieve data?
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Peter Perkins
le 28 Août 2019
You have a fixed-width file, and readtable needs to be told how it's organized, using fixedWidthImportOptions:
>> opts = fixedWidthImportOptions('NumVariables',7,...
'DataLines',2,...
'VariableNames',["Ind" "Mo" "dy" "V1" "V2" "AW" "X"],...
'VariableWidths',[5 3 4 6 5 3 5],...
'VariableTypes',repmat("double",1,7));
>> T = readtable('sample.txt',opts)
T =
17×7 table
Ind Mo dy V1 V2 AW X
____ __ __ ____ ____ ___ ____
1974 6 28 39.2 25.6 3 0
1974 6 29 41.2 30.5 5 0
1974 6 30 40.3 31.2 7 0
1974 7 1 41.3 31.5 12 0
1974 7 2 43.3 31.3 20 0
1974 7 3 41.2 NaN 16 41.6
1974 7 4 34.3 21.4 14 54.5
1974 7 5 33.1 23.8 5 0
1974 7 6 36.2 28.9 6 0
1975 4 18 36.6 20.8 12 0
1975 4 19 37.4 21.1 5 0
1975 4 20 39.9 27 7 0
1975 4 21 39.5 27.3 9 0
1975 4 22 NaN NaN NaN NaN
1975 4 23 39.5 27.1 8 0
1975 4 24 37.7 26 10 0
1975 4 25 38.7 27.2 15 0
4 commentaires
Peter Perkins
le 30 Août 2019
Even though fixedWidthImportOptions was introduced in R2018b, you can try using detectImportOptions with file type 'fixedwidth'. Introduced in R2017a.
Plus de réponses (2)
KSSV
le 20 Mar 2019
Modifié(e) : KSSV
le 20 Mar 2019
Read about readtable. It will insert NaN's where ver values are missing.
T = readtable('sample.txt') ;
3 commentaires
Peter Perkins
le 28 Août 2019
That happens because readtable treats the file as space-delimited, when in fact it is fixed-width format. See my response below.
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