I would like to grab a number from a string.
The string is: "responseID: 1 is the return value";
Sometimes the number could be 1, or 3, 300, 3000...
I am trying to do this in objective C for the iphone.
I've tried NSPredicate and NSRegularExpression, but I can not seem to get the right regex to start with.
I tried "*[0-9]+*";
Does this return the "1" , "300" or whatever number to me when I call the regex?
Thank you!
\d+ should match 1 or more digits.
Sorry, I was able to search again and found exactly what I was looking for: see this:
Objective C: How to grab a number after a sub string from string
Related
Using q’s like function, how can we achieve the following match using a single regex string regstr?
q) ("foo7"; "foo8"; "foo9"; "foo10"; "foo11"; "foo12"; "foo13") like regstr
>>> 0111110b
That is, like regstr matches the foo-strings which end in the numbers 8,9,10,11,12.
Using regstr:"foo[8-12]" confuses the square brackets (how does it interpret this?) since 12 is not a single digit, while regstr:"foo[1[0-2]|[1-9]]" returns a type error, even without the foo-string complication.
As the other comments and answers mentioned, this can't be done using a single regex. Another alternative method is to construct the list of strings that you want to compare against:
q)str:("foo7";"foo8";"foo9";"foo10";"foo11";"foo12";"foo13")
q)match:{x in y,/:string z[0]+til 1+neg(-/)z}
q)match[str;"foo";8 12]
0111110b
If your eventual goal is to filter on the matching entries, you can replace in with inter:
q)match:{x inter y,/:string z[0]+til 1+neg(-/)z}
q)match[str;"foo";8 12]
"foo8"
"foo9"
"foo10"
"foo11"
"foo12"
A variation on Cillian’s method: test the prefix and numbers separately.
q)range:{x+til 1+y-x}.
q)s:"foo",/:string 82,range 7 13 / include "foo82" in tests
q)match:{min(x~/:;in[;string range y]')#'flip count[x]cut'z}
q)match["foo";8 12;] s
00111110b
Note how unary derived functions x~/: and in[;string range y]' are paired by #' to the split strings, then min used to AND the result:
q)flip 3 cut's
"foo" "foo" "foo" "foo" "foo" "foo" "foo" "foo"
"82" ,"7" ,"8" ,"9" "10" "11" "12" "13"
q)("foo"~/:;in[;string range 8 12]')#'flip 3 cut's
11111111b
00111110b
Compositions rock.
As the comments state, regex in kdb+ is extremely limited. If the number of trailing digits is known like in the example above then the following can be used to check multiple patterns
q)str:("foo7"; "foo8"; "foo9"; "foo10"; "foo11"; "foo12"; "foo13"; "foo3x"; "foo123")
q)any str like/:("foo[0-9]";"foo[0-9][0-9]")
111111100b
Checking for a range like 8-12 is not currently possible within kdb+ regex. One possible workaround is to write a function to implement this logic. The function range checks a list of strings start with a passed string and end with a number within the range specified.
range:{
/ checking for strings starting with string y
s:((c:count y)#'x)like y;
/ convert remainder of string to long, check if within range
d:("J"$c _'x)within z;
/ find strings satisfying both conditions
s&d
}
Example use:
q)range[str;"foo";8 12]
011111000b
q)str where range[str;"foo";8 12]
"foo8"
"foo9"
"foo10"
"foo11"
"foo12"
This could be made more efficient by checking the trailing digits only on the subset of strings starting with "foo".
For your example you can pad, fill with a char, and then simple regex works fine:
("."^5$("foo7";"foo8";"foo9";"foo10";"foo11";"foo12";"foo13")) like "foo[1|8-9][.|0-2]"
I have the following Powershell variable
$var = "AB-0045"
I would like to increase the number in the string to become "AB-0046".
I can do:
$newNumber = [int]$var.Substring($var.length -4,4) + 1
Which will give me the desired number 46, but then I have to append that 46 as a string to a new string "AB-00".
Is there a better way to do that?
Now that you have the integer, you'll have to convert back to string formatted in the way you'd like and concatenate.
I'd recommend adding to "AB-" rather than "AB-00" in case your number goes over 100.
To pad leading zeros, you can use the -f operator.
e.g. "{0:d4}" -f 45
You'll still need to get the integer first (45 in the example) from your original string.
I tested with regex class Replace() method and string class Split() method with string formatter. Split() seems faster provided your string is always in the same format. The Replace() method does not care what happens before the last 4 numbers:
# Replace Method
[regex]::Replace($var,'\d{4}$',{([int]$args[0].Value+1).ToString('0000')})
# Split method
$a,[int]$b = $var.split('-'); "{0}-{1:0000}" -f $a,++$b
I'm trying to check if a string contains one of four sub strings in a simpler way than this:
if (imageUrl.contains('.jpg') ||
imageUrl.contains('.png') ||
imageUrl.contains('.tif') ||
imageUrl.contains('.gif')) {
}
Is there a way to do this? For example checking against a list?
You can use a regex pattern instead of a simple string:
imageUrl.contains(new RegExp("\.(jpg|png|tif|gif)"))
Might be somewhat simpler.
RegularExpression can solve your problem. RegEx are used to search patterns in strings.
RegEx example:
^The matches any string that starts with The
end$ matches a string that ends with end
^The end$ exact string match (starts and ends with The end)
abc* matches a string that has ab followed by zero or more c
I have a string and I need two characters to be returned.
I tried with strsplit but the delimiter must be a string and I don't have any delimiters in my string. Instead, I always want to get the second number in my string. The number is always 2 digits.
Example: 001a02.jpg I use the fileparts function to delete the extension of the image (jpg), so I get this string: 001a02
The expected return value is 02
Another example: 001A43a . Return values: 43
Another one: 002A12. Return values: 12
All the filenames are in a matrix 1002x1. Maybe I can use textscan but in the second example, it gives "43a" as a result.
(Just so this question doesn't remain unanswered, here's a possible approach: )
One way to go about this uses splitting with regular expressions (MATLAB's strsplit which you mentioned):
str = '001a02.jpg';
C = strsplit(str,'[a-zA-Z.]','DelimiterType','RegularExpression');
Results in:
C =
'001' '02' ''
In older versions of MATLAB, before strsplit was introduced, similar functionality was achieved using regexp(...,'split').
If you want to learn more about regular expressions (abbreviated as "regex" or "regexp"), there are many online resources (JGI..)
In your case, if you only need to take the 5th and 6th characters from the string you could use:
D = str(5:6);
... and if you want to convert those into numbers you could use:
E = str2double(str(5:6));
If your number is always at a certain position in the string, you can simply index this position.
In the examples you gave, the number is always the 5th and 6th characters in the string.
filename = '002A12';
num = str2num(filename(5:6));
Otherwise, if the formating is more complex, you may want to use a regular expression. There is a similar question matlab - extracting numbers from (odd) string. Modifying the code found there you can do the following
all_num = regexp(filename, '\d+', 'match'); %Find all numbers in the filename
num = str2num(all_num{2}) %Convert second number from str
I want to grab the first char of a var string and the first char of the following caracter
Example:
$var1 = "Jean-Martin"
I want a way to grab the first letter "J" then I want to take the first char following the "-" (dash) which is "M".
Something like this?
$initial1 = $var1[0]
$initial2 = $var1.Split('-')[1][0]
Strings in Powershell use the System.String class from the .Net framework. As such, they are indexable to retrieve individual characters and have many methods available such as the Split method used above.
See the documentation here.
$var1 = "Jean-Martin"
To get the first character:
$var1[0]
To get the first character after the dash:
$characterToSeek = '-'
$var1[$var1.IndexOf($characterToSeek)+1]
Another option using regex:
PS> $var1 -replace '^(.)[^-]+-(.).+$','$1$2'
JM