Hello
after doing the parsing with a script in Haskell I got a file with the 'appearance' of lists of strings. However when I call the file content with the function getContents or hGetContents, ie, reading the contents I get something like: String with lines (schematically what I want is: "[" aaa "," bbb "" ccc "]" -> ["aaa", "bbb" "ccc"]). I have tried with the read function but without results. I need to work with these lists of strings to concatenating them all in a single list.
I'm using the lines function, but I think it only 'works' one line at a time, doesn't it?
What I need is a function that verify if an element of a line is repeted on other line. If I could have a list of a list of strings it could be easier (but what I have is a line of a string that looks like a list of strings)
Regards
Thanks.
I have tried with the read function but without results
Just tested, and it works fine:
Prelude> read "[\"aaa\",\"bbb\",\"ccc\"]" :: [String]
["aaa","bbb","ccc"]
Note that you need to give the return type explicitly, since it can't be determined from the type of the argument.
I think the function you are looking for is the lines function from Data.List (reexported by the Prelude) that breaks up a multi-line string into a list of strings.
in my understanding, what you can do is
create a function that receives a list of lists, each list is a line of the entire string, of the argument passed in, and checks if a element of a line occurs in other line.
then, this function passes the entire string, separated by lines using [lines][1].
Related
I have used GetText on an area of screen text and it has returned values separated by "\n". This is perfectly fine as there are line-breaks in the text and actually is exactly what I wanted, however, I want to convert the string into a list, splitting on the "\n".
My issue is that I get the following error from this line of foce:
put text split by "\\n" into itemList
Sensetalk compiler exception: syntax error - cant understand "n" at line.....
I initially thought there was a delimiting issue, having originally tried to split on "\n" so I switched to "\n" but the same error occurs..
How can you use the split function when there are escape sequences in the string?
many thanks
Depending on how OCR is reading this in, one of the predefined variables should be equivalent to your \n. I would expect this to work:
put text split by newline into itemList
You can find out more about predefined variables in SenseTalk here: https://docs.eggplantsoftware.com/studio/stk-restricted-words/#predefined-variables
tex1() seems to return all strings as follow:
tex1(hello);
{\it hello}
tex1("hello");
\mbox{ hello }
What variable must one use to change this handling via texput? e.g. if I would just like it to print strings literally? I'm using other Maxima commands (like printf and concat to produce strings that are then passed to tex1, and occasionally the default handling is causing issues.
I tried texput(""", ...) and texput("''", ...); the first wasn't accepted, the 2nd was, but did not change the output. I really have no clue for the non-quoted strings.
Let's be careful to distinguish symbols from strings. When you enter tex1(hello) then hello is a symbol, and when you enter tex1("hello") then "hello" is a string. Symbols are essentially names for items in a lookup table, which can store additional info (symbol properties) for each. Strings on the other hand are just (from Maxima's point of view) just a sequence of characters.
Anyway changing the output for all symbols or all strings is unfortunately not possible via texput. But with a one-line Lisp function, one can accomplish it. Try this: for symbols,
:lisp (defun tex-stripdollar (sym) (maybe-invert-string-case (symbol-name (stripdollar sym))))
and for strings,
:lisp (defun tex-string (str) str)
These are going to change some existing outputs, so you'll want to try it and see if it works for you.
In Erlang when you have a list of printable characters, its a string, but a string is also a list of items and all functions of a list can be applied onto a string. Really, the data structure string doesn't exist in Erlang.
Part of my code needs to be sure that something is not only a list, but it's a string. (A real string). It needs to separate lists e.g. [1,2,3,a,b,"josh"] , from string e.g. "Muzaaya".
The guard expression is_list/1 will say true for both strings and lists. There is no such guard as is_string/1 and so this means I need a code snippet will make sure that my data is a string.
A string in this case is a list of only printable (alphabetical, both cases, upper and lower), and may contain numbers e.g "Muzaaya2536 618 Joshua". I need a code snippet please (Erlang) that will check this for me and ensure that the variable is a string, not just a list. thanks
You have two functions in the module io_lib which can be helpful: io_lib:printable_list/1 and io_lib:printable_unicode_list/1 which test if the argument is a list of printable latin1 or unicode characters respectively.
using the isprint(3) definition of printable characters --
isprint(X) when X >= 32, X < 127 -> true;
isprint(_) -> false.
is_string(List) when is_list(List) -> lists:all(fun isprint/1, List);
is_string(_) -> false.
you won't be able to use it as a guard, though.
I have read a multiline file and converted it to a list with the following code:
Lines = string:tokens(erlang:binary_to_list(Binary), "\n"),
I converted it to a string to do some work on it:
Flat = string:join(Lines, "\r\n"),
I finished working on the string and now I need to convert it back to a multiline list, I tried to repeat the first snippet shown above but that never worked, I tried string:join and that didnt work.. how do i convert it back to a list just like it used to be (although now modified)?
Well that depends on the modifications you made on the flattened string.
string:tokens/2 will always explode a string using the separator you provide. So as long as your transformation preserves a specific string as separator between the individual substrings there should be no problem.
However, if you do something more elaborate and destructive in your transformation then the only way is to iterate on the string manually and construct the individual substrings.
Your first snippet above contains a call to erlang:binary_to_list/1 which first converts a binary to a string (list) which you then split with the call to string:tokens/2 which then join together with string:join/2. The result of doing the tokens then join as you have written it seems to be to convert it from a string containing lines separated by \n into one containing lines separated by \r\n. N.B. that this is a flat list of characters.
Is this what you intended?
What you should do now depends on what you mean by "I need to convert it back to a multiline list". Do you mean everything in a single list of characters (string), or in a nested list of lines where each line is a list of characters (string). I.e. if you ended up with
"here is line 1\r\nhere is line 2\r\nhere is line 3\r\n"
this already is a multiline line list, or do you mean
["here is line 1","here is line 2","here is line 3"]
Note that each "string" is itself a list of characters. What do you intend to do with it afterwards?
You have your terms confused. A string in any language is a sequence of integer values corresponding to a human-readable characters. Whether the representation of the value is a binary or a list does not matter, both are technically strings because of the data they contain.
That being said, you converted a binary string to a list string in your first set of instructions. To convert a list into a binary, you can call erlang:list_to_binary/1, or erlang:iolist_to_binary/1 if your list is not flat. For instance:
BinString = <<"this\nis\na\nstring">>.
ListString = "this\nis\na\nstring" = binary_to_list(BinString).
Words = ["this", "is", "a", "string"] = string:tokens(ListString, "\n").
<<"thisisastring">> = iolist_to_binary(Words).
Rejoined = "this\r\nis\r\na\r\nstring" = string:join(Words, "\r\n").
BinAgain = <<"this\r\nis\r\na\r\nstring">> = list_to_binary(Rejoined).
For your reference, the string module always expects a flat list (e.g., "this is a string", but not ["this", "is", "a", "string"]), except for string:join, which takes a list of flat strings.
In Erlang when you have a list of printable characters, its a string, but a string is also a list of items and all functions of a list can be applied onto a string. Really, the data structure string doesn't exist in Erlang.
Part of my code needs to be sure that something is not only a list, but it's a string. (A real string). It needs to separate lists e.g. [1,2,3,a,b,"josh"] , from string e.g. "Muzaaya".
The guard expression is_list/1 will say true for both strings and lists. There is no such guard as is_string/1 and so this means I need a code snippet will make sure that my data is a string.
A string in this case is a list of only printable (alphabetical, both cases, upper and lower), and may contain numbers e.g "Muzaaya2536 618 Joshua". I need a code snippet please (Erlang) that will check this for me and ensure that the variable is a string, not just a list. thanks
You have two functions in the module io_lib which can be helpful: io_lib:printable_list/1 and io_lib:printable_unicode_list/1 which test if the argument is a list of printable latin1 or unicode characters respectively.
using the isprint(3) definition of printable characters --
isprint(X) when X >= 32, X < 127 -> true;
isprint(_) -> false.
is_string(List) when is_list(List) -> lists:all(fun isprint/1, List);
is_string(_) -> false.
you won't be able to use it as a guard, though.