Convert vector of characters to doubles/numeric

Hi,

I have a column of characters I would like to convert to doubles

'1.0118'
'1.0075'
'1.0064'
'1.0077'
'1.0087'
'1.0213'
'1.0213'
'1.013'
'1.013'
'1.0047'
'1.0039'
'0.9993'
'1.0059'
'1.0047'
'0.9985'

I have tried using str2double but it doesn't seem to work. How would I go about converting this into a column of doubles?

Thank you

Answer 1

[Ameer Hamza]

Is it available as a cell array. If yes, then try this

x = {
'1.0118'
'1.0075'
'1.0064'
'1.0077'
'1.0087'
'1.0213'
'1.0213'
'1.013'
'1.013'
'1.0047'
'1.0039'
'0.9993'
'1.0059'
'1.0047'
'0.9985'};

y = cellfun(@str2num, x)

[James Higgins]

Thank you Ameer but this did not work becuase it is a char array. Do have any suggestions for this?

[Ameer Hamza]

In MATLAB, character arrays cannot have a different number of characters in rows. For example

'1.0213'
'1.013'
'1.013'
'1.0047'

such a thing is not possible in a MATLAB array. Can you show in which form you have the characters? Maybe attach the variable in a .mat file.

[James Higgins]

So I am working with online data so I can't share the exact code becuase the API key to access the data is unique to the user. But I have attached a mat file below and also a screenshot of the original data location.

I am interested in extracting the column S.observations.value and transforming it from a character to double so that I can work with the data.

[Ameer Hamza]

The screenshot is enough to give the idea. You can do something like this

numeric_values = str2double({S.Observations.value})

[Walter Roberson]

str2double(value)

[James Higgins]

Thank you Ameer and Walter, this worked well. I guess I was missing something with the brackets!

I am also interested in extracting the dates from the 'date column and turning them into Matlab dates so that i could graph the values.

I have tried running

date = datetime((S.observations.date), 'InputFormat','yyyy-MM-dd')

but this seems not to work. I am following the Matlab 'datetime' format to turn characters into dates but it does not seem to work. Do you have any suggestions?

Thank you again for all your help.

[Ameer Hamza]

You need to use braces instead of parenthesis

date = datetime({S.observations.date}, 'InputFormat','yyyy-MM-dd')

[James Higgins]

Thank you! This worked perfectly

Answer 2

[Walter Roberson]

str2double(cellstr(YourCharacterArray))