From char to number
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Hi ,
I have this:
"10:58",297.98,0.25,0.15,66.5,1.194,-0.31,-0.27,71.1,0.966,""
it is of type char.
it contains the following numbers and one time value:
10:58 (time)
297.98
0.25
0.15
66.5
1.194
-0.31
-0.27
71.1
0.966
how can i convert this char type to individual numbers? I could not find it on internet i tried multiple things with char2[anything]
many thanks,
Paul
回答（4 个）
Walter Roberson
2015-5-12
S = '"10:58",297.98,0.25,0.15,66.5,1.194,-0.31,-0.27,71.1,0.966,""';
C = textscan(S, '"%[^"]",%f,%f,%f,%f,%f,%f,%f,%f,%f,%*s', 'CollectOutput', 1);
thetimestr = C{1}{1};
thenums = C{2};
9 个评论
paul kaam
2015-5-12
Walter Roberson
2015-5-12
A string is a char array, not a different datatype.
I tested the code, so if you copy and paste it, it should work
paul kaam
2015-5-12
Walter Roberson
2015-5-12
When I assign that text into a string it works. I deduce that there must be some extra invisible characters. Please run again and when it errors out, show both S (the visible string) and
S+0
which will show the character codes associated with each string position
paul kaam
2015-5-12
Walter Roberson
2015-5-12
You did not open the file with 'rt' to read in text mode.
Walter Roberson
2015-5-12
That is, the carriage return on the end was telling textscan that there was another line to process with the format, but then there was no text to process so the match against '"' could not take place.
paul kaam
2015-5-12
paul kaam
2015-5-12
omax ali
2020-11-5
0 个投票
i just write this for new ones who searching:
to change some value like a=["1","2.2","3",......] to number format we can do as:
b=char(a);
c=str2num(b);
c gives you the numbers.
1 个评论
a=["1","2.2","3"]
double(a)
This relies upon a being datatype string and not cell array of character vector:
a = {'1', '2.2', '3'}
str2double(a)
Again for someone stumbling over this:
if this is your char array: ' "10:58 ", 297.98, 0.25, 0.15, 66.5, 1.194, -0.31, -0.27, 71.1, 0.966,"" '
and these are your values:
val1 (1,1) datetime = 10:58
val2 (1,1) double = 297.98
...
val10 (1,1) double = 0.966
First of all, i want to say something about the array itself; you don't need any qotation marks around the time, it's arbitrary since you already have a char array. Next is the "" at the end, if it is supposed to be a empty string it's fine, otherwise remove it.
This applies if you're indexing stays the same for other arrays you may want to decode, if the indexing varries for some reasons there are better ways of doing dynamic identification.
Generally, I would advise against using char arrays to pass around data. If you have to do it or read from a text file make sure what you save is compatible with sscanf, fscanf, readtable or anything using Matlabs format spec. Json works as well with jsonencode and jsondecode.
if you can't get around it, I found the following to work:
value_char = '"10:58",297.98,0.25,0.15,66.5,1.194,-0.31,-0.27,71.1,0.966,""';
value_char = erase(value_char,'"');
value_cellstr = split(value_char,',');
time_str = string(value_cellstr{1});
value_time = datetime(time_str,InputFormat='HH:mm')
num_cellstr = value_cellstr(2:end-1);
nums = cellfun(@str2num,num_cellstr)
last_str = erase(value_cellstr{end},'"');
last_str = string(last_str)
This isn't the best implementation but it shows what you can do. Split the array into cell string using ',' as a delimiter then convert the individual cellstirngs to the format you want.
If you want it more adaptive you can also write a small function to use for cellfun, which identifies what type you want a value in and then does the conversion. Which might look something like this:
value_char = '"10:58",297.98,0.25,0.15,66.5,1.194,-0.31,-0.27,71.1,0.966,""';
value_cellstr = split(value_char,',');
nums = cellfun(@convert2type,value_cellstr,UniformOutput=false)
function A_convert = convert2type(A)
arguments
A char {mustBeTextScalar}
end
if contains(A,'"')
A_convert = erase(A,'"');
A_convert = string(A_convert);
else
A_convert = str2num(A);
end
end
If you want the time as a datetime just add a condition with ':' to the function in the function.
Bit of along answer but I hope it helps someone having to work with these things.
Edit: By default datetime automatically determines the display format if you only want daytime use Format='preserveinput'
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2023-6-24
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