# how to extract double value from a string?

38 vues (au cours des 30 derniers jours)
Happy PhD le 17 Fév 2023
Commenté : Luca Ferro le 17 Fév 2023
I been trying to figure our how to extract certain numbers from a string with this layout:
D:\MATLAB\noise_check\bilder\Image_230217_1227_Temp_ 42,75.png"
I want to extract the value 42.75 from it. Any ideas how I can do this?
I tried this but it gives me NaN as result:
V = str2double(regexp(fullFileNames,'\d+','match'))
This gives error "Error using sscanf, first argument mustnbe a text scalar".
d = sscanf(fullFileNames, '%d %d %d')
Thanks
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### Réponse acceptée

Dyuman Joshi le 17 Fév 2023
Déplacé(e) : Star Strider le 17 Fév 2023
"I tried this but it gives me NaN as result: "
Does it? Let's check -
str = "D:\MATLAB\noise_check\bilder\Image_230217_1227_Temp_ 42,75.png";
V = str2double(regexp(str,'\d+','match'))
V = 1×4
230217 1227 42 75
out = str2double(replace(regexp(str, '\d+,\d+', 'match'),',','.'))
out = 42.7500
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Happy PhD le 17 Fév 2023
Modifié(e) : Happy PhD le 17 Fév 2023
My strings are an cell array so maybe thats why it doesn't work.

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### Plus de réponses (1)

Luca Ferro le 17 Fév 2023
Modifié(e) : Luca Ferro le 17 Fév 2023
assuming the string is always formatted as such you could just:
s='D:\MATLAB\noise_check\bilder\Image_230217_1227_Temp_ 42,75.png'
numS=s(end-8:end-4);
numS2D=replace(numS(',','.'); %necessary since the conversion to double needs . and not ,
numD=str2double(numS2D)
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VBBV le 17 Fév 2023
s='D:\MATLAB\noise_check\bilder\Image_230217_1227_Temp_ 42,75.png'
s = 'D:\MATLAB\noise_check\bilder\Image_230217_1227_Temp_ 42,75.png'
numS=s(end-8:end-4)
numS = '42,75'
numS2D=replace(numS,',','.'); % may be you mean this
numD=str2double(numS2D)
numD = 42.7500
Luca Ferro le 17 Fév 2023
yep, typo. Thanks for the correction

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