Strings are converted to cells during readtable

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I am incrementally saving data to a csv file which includes strings:
data = table("string1", "string2");
writetable(data, "data.csv");
Later on:
data_from_file = readtable('data.csv')
data_from_file =
1×2 table
Var1 Var2
___________ ___________
{'string1'} {'string2'}
Note that the data are now char arrays in cells.
This is causing lots of problems, for example when I try to join the old data with the new:
new_data = table("string1", "string2");
data = outerjoin(data_from_file, new_data, 'MergeKeys', true)
Error using tabular/outerjoin (line 152)
Left and right key variables 'Var1' and 'Var1' are not comparable because one is
a non-cell.
Is there a way to avoid this problem or convert the chars back to strings after readtable?

Accepted Answer

Stephen23
Stephen23 on 10 Jun 2022
Edited: Stephen23 on 10 Jun 2022
The simple solution is to specify the TEXTTYPE option when importing:
data = table("string1", "string2");
writetable(data, "data.csv");
data_from_file = readtable('data.csv', 'TextType','string')
data_from_file = 1×2 table
Var1 Var2 _________ _________ "string1" "string2"

More Answers (1)

KSSV
KSSV on 10 Jun 2022
You can convert cell into a string and then use join.
data = table("string1", "string2");
writetable(data, "data.csv");
data_from_file = readtable('data.csv') ;
for i = 1:width(data_from_file)
data_from_file.(i) = string(data_from_file.(i)) ;
end
new_data = table("string3", "string4");
data = outerjoin(data_from_file, new_data, 'MergeKeys', true)

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