Differentiating widths of a string in Presto (zero-width characters) - presto

I'd like to compare string lengths in bytes of a field, because the field could have some zero-width characters in it.
The Binary functions seem most relevant, but it seems they all expect length-one input and I can't figure any way to split out the string to individual rows.
e.g.
select from_hex('abc')
gives error
invalid input length 3
And I can't "split on nothing" to convert this to 3 rows (a, b, c separately):
select split('abc', '')
The delimiter may not be the empty string
In R, I'm accustomed to the nchar function where I can specify type = 'bytes' (count by bytes), 'chars' (matches Presto's length from what I've seen), or 'width' (zero-width characters don't count -- the visible width of the string), and where strsplit('abc', NULL) or strsplit('abc', '') give list(c('a', 'b', 'c')).
I'm not sure I can copy-paste a string with a zero-width character here so here's R code to create one:
rawToChar(as.raw(c(0x68, 0x65, 0x6c, 0x6c, 0x6F, 0xe2, 0x80, 0x8d)))
with Presto length output:
select length('hello‍')
In R, I can get three different widths of this string:
sapply(c('width', 'chars', 'bytes'), x = 'hello‍')
# width chars bytes
# 5 6 8
Is there any way to replicate this in Presto?

Related

Find biggest element in a String with words?

How can I, in ABAP, split a string into n parts AND determine which one is the biggest element? In my solution I would need to know how many elements there are, but I want to solve it for WHATEVER NUMBER of elements.
I tried the below code. And i searched the web.
DATA: string TYPE string VALUE 'this is a string'.
DATA: part1 TYPE c LENGTH 20.
DATA: part2 TYPE c LENGTH 20.
DATA: part3 TYPE c LENGTH 20.
DATA: part4 TYPE c LENGTH 20.
DATA: del TYPE c VALUE ' '.
DATA: bigger TYPE c LENGTH 20.
split: string AT del INTO part1 part2 part3 part4.
bigger = part1.
IF bigger > part2.
bigger = part1.
ELSEIF bigger > part3.
bigger = part2.
ELSE.
bigger = part4.
ENDIF.
WRITE: bigger.
Expected result: Works with any number of elements in a string and determines which one is biggest.
Actual result: I need to know how many elements there are
Here is one way to solve it:
DATA: string TYPE string VALUE 'this is a string'.
TYPES: BEGIN OF ty_words,
word TYPE string,
length TYPE i,
END OF ty_words.
DATA: ls_words TYPE ty_words.
DATA: gt_words TYPE STANDARD TABLE OF ty_words.
START-OF-SELECTION.
WHILE string IS NOT INITIAL.
SPLIT string AT space INTO ls_words-word string.
ls_words-length = strlen( ls_words-word ).
APPEND ls_words TO gt_words.
ENDWHILE.
SORT gt_words BY length DESCENDING.
READ TABLE gt_words
ASSIGNING FIELD-SYMBOL(<ls_longest_word>)
INDEX 1.
IF sy-subrc EQ 0.
WRITE: 'The longest word is:', <ls_longest_word>-word.
ENDIF.
Please note, it does not cover the case if there are more longest words with the same length, it will just show one of them.
You don't need to know the number of splitted parts if you split the string into an array. Then you LOOP over the array and check the string length to find the longest one.
While József Szikszai's solution works, it may be too complex for the functionality you need. This would work just as well: (also with the same limitation that it willl only output the first longest word and no other ones of the same length)
DATA string TYPE string VALUE 'this is a string'.
DATA parts TYPE STANDARD TABLE OF string.
DATA biggest TYPE string.
FIELD-SYMBOLS <part> TYPE string.
SPLIT string AT space INTO TABLE parts.
LOOP AT parts ASSIGNING <part>.
IF STRLEN( <part> ) > STRLEN( biggest ).
biggest = <part>.
ENDIF.
ENDLOOP.
WRITE biggest.
Edit: I assumed 'biggest' meant longest, but if you actually wanted the word that would be last in an alphabet, then you could sort the array descending and just output the first entry like this:
DATA string TYPE string VALUE 'this is a string'.
DATA parts TYPE STANDARD TABLE OF string.
DATA biggest TYPE string.
SPLIT string AT space INTO TABLE parts.
SORT parts DESCENDING.
READ TABLE parts INDEX 1 INTO biggest.
WRITE biggest.
With ABAP 740, you can also shorten it to:
SPLIT lv_s AT space INTO TABLE DATA(lt_word).
DATA(lv_longest) = REDUCE string( INIT longest = `` FOR <word> IN lt_word NEXT longest = COND #( WHEN strlen( <word> ) > strlen( longest ) THEN <word> ELSE longest ) ).
DATA(lv_alphabetic) = REDUCE string( INIT alph = `` FOR <word> IN lt_word NEXT alph = COND #( WHEN <word> > alph THEN <word> ELSE alph ) ).
If "biggest" means "longest" word here is the Regex way to do this:
FIND ALL OCCURRENCES OF REGEX '\w+' IN string RESULTS DATA(words).
SORT words BY length DESCENDING.
WRITE substring( val = string off = words[ 1 ]-offset len = words[ 1 ]-length ).

Lua: string of specific length

local data = "here is a string"
local no = 12
foo = string.format("%50s %05d",data,no)
print(foo:len(),string.format("%q",foo))
defines foo as a string of specific length
" here is a string 00012"
However, is there an easy way to get
"here is a string 00012"
I know, that I can fill up the string data with spaces
while data:len() < 50 do data = data.." " end
Add a minus to format string %-50s to align text to the left:
foo = string.format("%-50s %05d","here is a string", 12)
print(foo:len(), foo)
Output:
56 here is a string 00012
Allowed flags:
- : left align result inside field
+ : always prefix with a sign, using + if field positive
0 : left-fill with zeroes rather than spaces
(space) : If positive, put a space where the + would have been
# : Changes the behaviour of various formats, as follows:
For octal conversion (o), prefixes the number with 0 - if necessary.
For hex conversion (x), prefixes the number with 0x
For hex conversion (X), prefixes the number with 0X
For e, E and f formats, always show the decimal point.
For g and G format, always show the decimal point, and do not truncate trailing zeroes.
The option to 'always show the decimal point' would only apply if you had the precision set to 0.

How to compute word scores in Scrabble using MATLAB

I have a homework program I have run into a problem with. We basically have to take a word (such as MATLAB) and have the function give us the correct score value for it using the rules of Scrabble. There are other things involved such as double word and double point values, but what I'm struggling with is converting to ASCII. I need to get my string into ASCII form and then sum up those values. We only know the bare basics of strings and our teacher is pretty useless. I've tried converting the string into numbers, but that's not exactly working out. Any suggestions?
function[score] = scrabble(word, letterPoints)
doubleword = '#';
doubleletter = '!';
doublew = [findstr(word, doubleword)]
trouble = [findstr(word, doubleletter)]
word = char(word)
gameplay = word;
ASCII = double(gameplay)
score = lower(sum(ASCII));
Building on Francis's post, what I would recommend you do is create a lookup array. You can certainly convert each character into its ASCII equivalent, but then what I would do is have an array where the input is the ASCII code of the character you want (with a bit of modification), and the output will be the point value of the character. Once you find this, you can sum over the points to get your final point score.
I'm going to leave out double points, double letters, blank tiles and that whole gamut of fun stuff in Scrabble for now in order to get what you want working. By consulting Wikipedia, this is the point distribution for each letter encountered in Scrabble.
1 point: A, E, I, O, N, R, T, L, S, U
2 points: D, G
3 points: B, C, M, P
4 points: F, H, V, W, Y
5 points: K
8 points: J, X
10 points: Q, Z
What we're going to do is convert your word into lower case to ensure consistency. Now, if you take a look at the letter a, this corresponds to ASCII code 97. You can verify that by using the double function we talked about earlier:
>> double('a')
97
As there are 26 letters in the alphabet, this means that going from a to z should go from 97 to 122. Because MATLAB starts indexing arrays at 1, what we can do is subtract each of our characters by 96 so that we'll be able to figure out the numerical position of these characters from 1 to 26.
Let's start by building our lookup table. First, I'm going to define a whole bunch of strings. Each string denotes the letters that are associated with each point in Scrabble:
string1point = 'aeionrtlsu';
string2point = 'dg';
string3point = 'bcmp';
string4point = 'fhvwy';
string5point = 'k';
string8point = 'jx';
string10point = 'qz';
Now, we can use each of the strings, convert to double, subtract by 96 then assign each of the corresponding locations to the points for each letter. Let's create our lookup table like so:
lookup = zeros(1,26);
lookup(double(string1point) - 96) = 1;
lookup(double(string2point) - 96) = 2;
lookup(double(string3point) - 96) = 3;
lookup(double(string4point) - 96) = 4;
lookup(double(string5point) - 96) = 5;
lookup(double(string8point) - 96) = 8;
lookup(double(string10point) - 96) = 10;
I first create an array of length 26 through the zeros function. I then figure out where each letter goes and assign to each letter their point values.
Now, the last thing you need to do is take a string, take the lower case to be sure, then convert each character into its ASCII equivalent, subtract by 96, then sum up the values. If we are given... say... MATLAB:
stringToConvert = 'MATLAB';
stringToConvert = lower(stringToConvert);
ASCII = double(stringToConvert) - 96;
value = sum(lookup(ASCII));
Lo and behold... we get:
value =
10
The last line of the above code is crucial. Basically, ASCII will contain a bunch of indexing locations where each number corresponds to the numerical position of where the letter occurs in the alphabet. We use these positions to look up what point / score each letter gives us, and we sum over all of these values.
Part #2
The next part where double point values and double words come to play can be found in my other StackOverflow post here:
Calculate Scrabble word scores for double letters and double words MATLAB
Convert from string to ASCII:
>> myString = 'hello, world';
>> ASCII = double(myString)
ASCII =
104 101 108 108 111 44 32 119 111 114 108 100
Sum up the values:
>> total = sum(ASCII)
total =
1160
The MATLAB help for char() says (emphasis added):
S = char(X) converts array X of nonnegative integer codes into a character array. Valid codes range from 0 to 65535, where codes 0 through 127 correspond to 7-bit ASCII characters. The characters that MATLAB® can process (other than 7-bit ASCII characters) depend upon your current locale setting. To convert characters into a numeric array, use the double function.
ASCII chart here.

how to convert a double array to character string

hello i have entered some text and convert it to the binary values.these binary values get stored in a array of data type double. Now i want to get the char array from that array containing binary values.
text2='hello how are u';
text3=double(text2);
nValues = numel(text3);
B=8;
bit_stream = zeros(1,nValues*B);
% eight bit for binary representation of each character.
for iBit = 1:B %# Loop over the bits
bit_stream(iBit:B:end) = bitget(text3,B-iBit+1); %# Get the bit values
end
bitstream=bit_stream;
how to perform vice-versa..
text2_recovered = char( 2.^(7:-1:0) * reshape(bit_stream, 8, []) );
Explanation:
Arrange bits in groups of 8 (reshape(...,8,[]));
Convert each group to a byte value (2.^(7:-1:0)*...) ;
Convert those bytes to characters (char).

How compiler is converting integer to string and vice versa

Many languages have functions for converting string to integer and vice versa. So what happens there? What algorithm is being executed during conversion?
I don't ask in specific language because I think it should be similar in all of them.
To convert a string to an integer, take each character in turn and if it's in the range '0' through '9', convert it to its decimal equivalent. Usually that's simply subtracting the character value of '0'. Now multiply any previous results by 10 and add the new value. Repeat until there are no digits left. If there was a leading '-' minus sign, invert the result.
To convert an integer to a string, start by inverting the number if it is negative. Divide the integer by 10 and save the remainder. Convert the remainder to a character by adding the character value of '0'. Push this to the beginning of the string; now repeat with the value that you obtained from the division. Repeat until the divided value is zero. Put out a leading '-' minus sign if the number started out negative.
Here are concrete implementations in Python, which in my opinion is the language closest to pseudo-code.
def string_to_int(s):
i = 0
sign = 1
if s[0] == '-':
sign = -1
s = s[1:]
for c in s:
if not ('0' <= c <= '9'):
raise ValueError
i = 10 * i + ord(c) - ord('0')
return sign * i
def int_to_string(i):
s = ''
sign = ''
if i < 0:
sign = '-'
i = -i
while True:
remainder = i % 10
i = i / 10
s = chr(ord('0') + remainder) + s
if i == 0:
break
return sign + s
I wouldn't call it an algorithm per se, but depending on the language it will involve the conversion of characters into their integral equivalent. Many languages will either stop on the first character that cannot be represented as an integer (e.g. the letter a), will blindly convert all characters into their ASCII value (e.g. the letter a becomes 97), or will ignore characters that cannot be represented as integers and only convert the ones that can - or return 0 / empty. You have to get more specific on the framework/language to provide more information.
String to integer:
Many (most) languages represent strings, on some level or another, as an array (or list) of characters, which are also short integers. Map the ones corresponding to number characters to their number value. For example, '0' in ascii is represented by 48. So you map 48 to 0, 49 to 1, and so on to 9.
Starting from the left, you multiply your current total by 10, add the next character's value, and move on. (You can make a larger or smaller map, change the number you multiply by at each step, and convert strings of any base you like.)
Integer to string is a longer process involving base conversion to 10. I suppose that since most integers have limited bits (32 or 64, usually), you know that it will come to a certain number of characters at most in a string (20?). So you can set up your own adder and iterate through each place for each bit after calculating its value (2^place).

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