I am trying to format a numeric number to display in exponential form. e.g 140500.45 as 1.4050045E5 using NumberFormat class in Dart. How do i go about this in flutter.
The following is what i have tried so far;
`NumberFormat numbFormat = NumberFormat("E", "en_US");
returnFormat = numbFormat.format(numericNumber);
print(returnFormat);`
Thanks.
This is how i eventually solved the problem;
double resultme = 140500.45;
double myreturnFormat = resultMe;
returnFormat = myreturnFormat.toStringAsExponential();
print(returnFormat);
The output is now correctly 1.4050045e+5
What i was initial doing wrong is supplying double argument to toStringAsExponential() method. The method requires no argument to return the results without rounding up the result. If you desire to return result such as 1.405e+5, do it like so;
myreturnFormat.toStringAsExponential(3);
The output will be 1.405e+5
Hope this help someone.
I have such code in controller's method for rounding (only higher) and display ceil part of number:
#constr_num.each do |cn|
non_original_temp_var2 = get_non_tecdoc_analogs(cn.ARL_SEARCH_NUMBER, #article.supplier.SUP_BRAND, false)
non_original << non_original_temp_var2
end
#non_original = non_original.flatten!
#non_original.each do |n_original|
n_original.price = my_round2(n_original.price * markup_for_user)
end
def my_round2 a
res = (a / 1.0).ceil * 1
res
end
But for some reasons i see with every price comma with 0 after it, for example: 5142.0 but it must be 5142
Main strange part is that, if i try to write:
n_original.price = 123
in view i see 123.0
What happend?
Only when i write in view (when displaying price):
price.ceil
i see normal numbers, without comma
What i di wrong? How to ceil my numbers with rounding (but only high, for example 2.24 is 3 3.51 is 4 and 2.0 is 2)? Becouse now for some reasons i see comma and nul after my number, even if i try to "hardcode" number in controller.
How about using the next or succ function of the Integer class? Try something like the following:
def my_round2 a
(a.is_a? Integer) ? a : a.to_i.next
end
If a is an Integer then return a otherwise cast it to Integer using the to_i method and call next or succ method on it.
Reference: http://www.ruby-doc.org/core-2.0/Integer.html
I guess I missed the second part of your question. To avoid the decimal places I guess you would have to use the a.to_i like Philip Hallstrom has suggested.
My guess is that your price field is a Float. Floats will be printed with a decimal spot by default. You need to either cast it to an Integer earlier on (say in my_round2 method) or in your view task a .to_i onto the output.
Easy question here, probably, but searching did not find a similar question.
The # operator finds the length of a string, among other things, great. But with Lua being dynamically typed, thus no conversion operators, how does one type a number as a string in order to determine its length?
For example suppose I want to print the factorials from 1 to 9 in a formatted table.
i,F = 1,1
while i<10 do
print(i.."! == "..string.rep("0",10-#F)..F)
i=i+1
F=F*i
end
error: attempt to get length of global 'F' (a number value)
why not use tostring(F) to convert F to a string?
Alternatively,
length = math.floor(math.log10(number)+1)
Careful though, this will only work where n > 0!
There are probably a dozen ways to do this. The easy way is to use tostring as Dan mentions. You could also concatenate an empty string, e.g. F_str=""..F to get F_str as a string representation. But since you are trying to output a formatted string, use the string.format method to do all the hard work for you:
i,F = 1,1
while i<10 do
print(string.format("%01d! == %010d", i, F))
i=i+1
F=F*i
end
Isn't while tostring(F).len < 10 do useful?
For example, if I want to read the middle value from magic(5), I can do so like this:
M = magic(5);
value = M(3,3);
to get value == 13. I'd like to be able to do something like one of these:
value = magic(5)(3,3);
value = (magic(5))(3,3);
to dispense with the intermediate variable. However, MATLAB complains about Unbalanced or unexpected parenthesis or bracket on the first parenthesis before the 3.
Is it possible to read values from an array/matrix without first assigning it to a variable?
It actually is possible to do what you want, but you have to use the functional form of the indexing operator. When you perform an indexing operation using (), you are actually making a call to the subsref function. So, even though you can't do this:
value = magic(5)(3, 3);
You can do this:
value = subsref(magic(5), struct('type', '()', 'subs', {{3, 3}}));
Ugly, but possible. ;)
In general, you just have to change the indexing step to a function call so you don't have two sets of parentheses immediately following one another. Another way to do this would be to define your own anonymous function to do the subscripted indexing. For example:
subindex = #(A, r, c) A(r, c); % An anonymous function for 2-D indexing
value = subindex(magic(5), 3, 3); % Use the function to index the matrix
However, when all is said and done the temporary local variable solution is much more readable, and definitely what I would suggest.
There was just good blog post on Loren on the Art of Matlab a couple days ago with a couple gems that might help. In particular, using helper functions like:
paren = #(x, varargin) x(varargin{:});
curly = #(x, varargin) x{varargin{:}};
where paren() can be used like
paren(magic(5), 3, 3);
would return
ans = 16
I would also surmise that this will be faster than gnovice's answer, but I haven't checked (Use the profiler!!!). That being said, you also have to include these function definitions somewhere. I personally have made them independent functions in my path, because they are super useful.
These functions and others are now available in the Functional Programming Constructs add-on which is available through the MATLAB Add-On Explorer or on the File Exchange.
How do you feel about using undocumented features:
>> builtin('_paren', magic(5), 3, 3) %# M(3,3)
ans =
13
or for cell arrays:
>> builtin('_brace', num2cell(magic(5)), 3, 3) %# C{3,3}
ans =
13
Just like magic :)
UPDATE:
Bad news, the above hack doesn't work anymore in R2015b! That's fine, it was undocumented functionality and we cannot rely on it as a supported feature :)
For those wondering where to find this type of thing, look in the folder fullfile(matlabroot,'bin','registry'). There's a bunch of XML files there that list all kinds of goodies. Be warned that calling some of these functions directly can easily crash your MATLAB session.
At least in MATLAB 2013a you can use getfield like:
a=rand(5);
getfield(a,{1,2}) % etc
to get the element at (1,2)
unfortunately syntax like magic(5)(3,3) is not supported by matlab. you need to use temporary intermediate variables. you can free up the memory after use, e.g.
tmp = magic(3);
myVar = tmp(3,3);
clear tmp
Note that if you compare running times with the standard way (asign the result and then access entries), they are exactly the same.
subs=#(M,i,j) M(i,j);
>> for nit=1:10;tic;subs(magic(100),1:10,1:10);tlap(nit)=toc;end;mean(tlap)
ans =
0.0103
>> for nit=1:10,tic;M=magic(100); M(1:10,1:10);tlap(nit)=toc;end;mean(tlap)
ans =
0.0101
To my opinion, the bottom line is : MATLAB does not have pointers, you have to live with it.
It could be more simple if you make a new function:
function [ element ] = getElem( matrix, index1, index2 )
element = matrix(index1, index2);
end
and then use it:
value = getElem(magic(5), 3, 3);
Your initial notation is the most concise way to do this:
M = magic(5); %create
value = M(3,3); % extract useful data
clear M; %free memory
If you are doing this in a loop you can just reassign M every time and ignore the clear statement as well.
To complement Amro's answer, you can use feval instead of builtin. There is no difference, really, unless you try to overload the operator function:
BUILTIN(...) is the same as FEVAL(...) except that it will call the
original built-in version of the function even if an overloaded one
exists (for this to work, you must never overload
BUILTIN).
>> feval('_paren', magic(5), 3, 3) % M(3,3)
ans =
13
>> feval('_brace', num2cell(magic(5)), 3, 3) % C{3,3}
ans =
13
What's interesting is that feval seems to be just a tiny bit quicker than builtin (by ~3.5%), at least in Matlab 2013b, which is weird given that feval needs to check if the function is overloaded, unlike builtin:
>> tic; for i=1:1e6, feval('_paren', magic(5), 3, 3); end; toc;
Elapsed time is 49.904117 seconds.
>> tic; for i=1:1e6, builtin('_paren', magic(5), 3, 3); end; toc;
Elapsed time is 51.485339 seconds.
I need a well tested Regular Expression (.net style preferred), or some other simple bit of code that will parse a USA/CA phone number into component parts, so:
3035551234122
1-303-555-1234x122
(303)555-1234-122
1 (303) 555 -1234-122
etc...
all parse into:
AreaCode: 303
Exchange: 555
Suffix: 1234
Extension: 122
None of the answers given so far was robust enough for me, so I continued looking for something better, and I found it:
Google's library for dealing with phone numbers
I hope it is also useful for you.
This is the one I use:
^(?:(?:[\+]?(?<CountryCode>[\d]{1,3}(?:[ ]+|[\-.])))?[(]?(?<AreaCode>[\d]{3})[\-/)]?(?:[ ]+)?)?(?<Number>[a-zA-Z2-9][a-zA-Z0-9 \-.]{6,})(?:(?:[ ]+|[xX]|(i:ext[\.]?)){1,2}(?<Ext>[\d]{1,5}))?$
I got it from RegexLib I believe.
This regex works exactly as you want with your examples:
Regex regexObj = new Regex(#"\(?(?<AreaCode>[0-9]{3})\)?[-. ]?(?<Exchange>[0-9]{3})[-. ]*?(?<Suffix>[0-9]{4})[-. x]?(?<Extension>[0-9]{3})");
Match matchResult = regexObj.Match("1 (303) 555 -1234-122");
// Now you have the results in groups
matchResult.Groups["AreaCode"];
matchResult.Groups["Exchange"];
matchResult.Groups["Suffix"];
matchResult.Groups["Extension"];
Strip out anything that's not a digit first. Then all your examples reduce to:
/^1?(\d{3})(\d{3})(\d{4})(\d*)$/
To support all country codes is a little more complicated, but the same general rule applies.
Here is a well-written library used with GeoIP for instance:
http://highway.to/geoip/numberparser.inc
here's a method easier on the eyes provided by the Z Directory (vettrasoft.com),
geared towards American phone numbers:
string_o s2, s1 = "888/872.7676";
z_fix_phone_number (s1, s2);
cout << s2.print(); // prints "+1 (888) 872-7676"
phone_number_o pho = s2;
pho.store_save();
the last line stores the number to database table "phone_number".
column values: country_code = "1", area_code = "888", exchange = "872",
etc.