I am relatively new to maxima. I want to know how to write an array into a text file using maxima.
I know it's late in the game for the original post, but I'll leave this here in case someone finds it in a search.
Let A be a Lisp array, Maxima array, matrix, list, or nested list. Then:
write_data (A, "some_file.data");
Let S be an ouput stream (created by openw or opena). Then:
write_data (A, S);
Entering ?? numericalio at the input prompt, or ?? write_ or ?? read_, will show some info about this function and related ones.
I've never used maxima (or even heard of it), but a little Google searching out of curiousity turned up this: http://arachnoid.com/maxima/files_functions.html
From what I can gather, you should be able to do something like this:
stringout("my_new_file.txt",values);
It says the second parameter to the stringout function can be one or more of these:
input: all user entries since the beginning of the session.
values: all user variable and array assignments.
functions: all user-defined functions (including functions defined within any loaded packages).
all: all of the above. Such a list is normally useful only for editing and extraction of useful sections.
So by passing values it should save your array assignments to file.
A bit more necroposting, as google leads here, but I haven't found it useful enough. I've needed to export it as following:
-0.8000,-0.8000,-0.2422,-0.242
-0.7942,-0.7942,-0.2387,-0.239
-0.7776,-0.7776,-0.2285,-0.228
-0.7514,-0.7514,-0.2124,-0.212
-0.7168,-0.7168,-0.1912,-0.191
-0.6750,-0.6750,-0.1655,-0.166
-0.6272,-0.6272,-0.1362,-0.136
-0.5746,-0.5746,-0.1039,-0.104
So I've found how to do this with printf:
with_stdout(filename, for i:1 thru length(z_points) do
printf (true,"~,4f,~,4f,~,4f,~,3f~%",bot_points[i],bot_points[i],top_points[i],top_points[i]));
A bit cleaner variation on the #ProdoElmit's answer:
list : [1,2,3,4,5]$
with_stdout("file.txt", apply(print, list))$
/* 1 2 3 4 5 is then what appears in file.txt */
Here the trick with apply is needed as you probably don't want to have square brackets in your output, as is produced by print(list).
For a matrix to be printed out, I would have done the following:
m : matrix([1,2],[3,4])$
with_stdout("file.txt", for row in args(m) do apply(print, row))$
/* 1 2
3 4
is what you then have in file.txt */
Note that in my solution the values are separated with spaces and the format of your values is fixed to that provided by print. Another caveat is that there is a limit on the number of function parameters: for example, for me (GCL 2.6.12) my method does not work if length(list) > 64.
Related
The following is my sample code: https://play.openpolicyagent.org/p/oyY1GOsYaf
Here when I try to evaluate names array, it is showing:
error occurred: 1:1: rego_unsafe_var_error: var names is unsafe
But when I define the same comprehension outside the allow rule definition : https://play.openpolicyagent.org/p/Xv0cF7FM8b, I am able to evaluate the selection
[
"smoke",
"dev"]
could someone help me to point out the difference and if I want to define the comprehention inside the rule is there any syntax I need to follow? Thanks in advance
Note: I am getting the final output as expected in both cases, only issue is with the names array evaluation.
The way the Rego Playground generates a query when evaluating a selection is much more simplistic than one might assume. A query will be generated from your selected text, without taking into account where in the document that text was selected. This means that even if you select a local variable inside a rule body, the query will simply contain that variable name (names, in your case); which will be perceived as a reference to a top-level variable in the document's body, even though a rule-local variable was selected. This is why your first sample returns an error, as there is no top-level variable names in the document; whereas the second sample does, and therefore succeeds.
You can test this quirk by selecting and evaluating the word hello on line 3 here: https://play.openpolicyagent.org/p/n5OPoFnlhx.
package play
# hello
hello {
m := input.message
m == "world"
}
Even though it's just part of a comment, it'll evaluate just as if you had selected the rule name on line 5.
Acordding to the documentation of maxima, with_stdout is a function that evaluates some expressions and writes the output according to this expressions to a file f. I tried to use this function with a simple example:
with_stdout ("data.txt", for x:0 thru 10 do print (x, x^2, x^3))$
But the output look like this:
<mth><n>0</n><st> </st><n>0</n><st> </st><n>0</n><st> </st></mth><mth><n>1</n><st> </st><n>1</n><st> </st><n>1</n><st> </st></mth><mth><n>2</n><st> </st><n>4</n><st> </st><n>8</n><st> </st></mth><mth><n>3</n><st> </st><n>9</n><st> </st><n>27</n><st> </st></mth><mth><n>4</n><st> </st><n>16</n><st> </st><n>64</n><st> </st></mth><mth><n>5</n><st> </st><n>25</n><st> </st><n>125</n><st> </st></mth><mth><n>6</n><st> </st><n>36</n><st> </st><n>216</n><st> </st></mth><mth><n>7</n><st> </st><n>49</n><st> </st><n>343</n><st> </st></mth><mth><n>8</n><st> </st><n>64</n><st> </st><n>512</n><st> </st></mth><mth><n>9</n><st> </st><n>81</n><st> </st><n>729</n><st> </st></mth><mth><n>10</n><st> </st><n>100</n><st> </st><n>1000</n><st> </st></mth>
instead of writting a table with three columns as it is supposed to do.
I don't even understand the first output. What I am missunderstanding or missing here?
--
It seems there is a bug triggered by Wxmaxima, I don't know if it is on maxima aswell.
Regards.
Apparently wxMaxima overrides the default print function to generate XML tags (stuff like <foo> ... </foo>) which wxMaxima uses to indicate how stuff is displayed. I don't know if it's possible to directly call the default print function in wxMaxima; maybe, maybe not.
I can see a few options. (1) Call grind instead, which outputs the so-called 1-dimensional output. That's probably more suitable for file output anyway.
(2) Call printf, e.g. printf(true, "~a, ~a, ~a~%", x, x^2, x^3). printf recognizes many output options, as described by ? printf. It's possible printf calls are also intercepted by wxMaxima, I haven't tried it.
(3) Use the plain text, console Maxima interface, then print is sure to be the default.
I am trying to split this statement in Lua
sendex,000D6F0011BA2D60,fb,btn,1,on,100,null
i need output like this way:
Mac:000D6F0011BA2D60
Value:1
command:on
value:100
how to split and get the values?
local input = "sendex,000D6F0011BA2D60,fb,btn,1,on,100,null"
local buffer = {}
for word in input:gmatch('[^,]+') do
table.insert(buffer, word)
--print(word) -- uncomment this to see the words as they are being matched ;)
end
print("Mac:"..buffer[2])
print("Value:"..buffer[5])
...
For a complete explanation of what string.gmatch does, see the Lua reference. To summarize, it iterates over a string and searches for a pattern, in this case [^,]+, meaning all groups of 1 or more characters that aren't a comma. Every time it finds said pattern, it does something with it and continues searching.
If your input is exactly like you have described, the code below works:
s="sendex,000D6F0011BA2D60,fb,btn,1,on,100,null"
Mac,Value,command,value = s:match(".-,(.-),.-,.-,(.-),(.-),(.-),")
print(Mac,Value,command,value)
It uses the non-greedy pattern .- to split the input into fields. It also captures the relevant fields.
I'm trying to automate some output using printf but I'm struggling to find a way to pass to it the list of arguments expr_1, ..., expr_n in
printf (dest, string, expr_1, ..., expr_n)
I thought of using something like Javascript's spread operator but I'm not even sure I should need it.
For instace, say I have a list of strings to be output
a:["foo","bar","foobar"];
a string of appropriate format descriptors, say
s: "~a ~a ~a ~%";
and an output stream, say os. How can I invoke printf using these things in such a way that the result will be the same as writing
printf(os,s,a[1],a[2],a[3]);
Then I could generalize it to output lists of variable size.
Any suggestions?
Thanks.
EDIT:
I just learned about apply and, using the conditions I posed in my OP, the following seems to work wonderfully:
apply(printf,append([os,s],a));
Maxima printf implements most or maybe all of the formatting operators from Common Lisp FORMAT, which are quite extensive; see: http://www.lispworks.com/documentation/HyperSpec/Body/22_c.htm See also ? printf in Maxima to get an abbreviated list of formatting operators.
In particular for a list you can do something like:
printf (os, "my list: ~{~a~^, ~}~%", a);
to get the elements of a separated by ,. Here "~{...~}" tells printf to expect a list, and ~a is how to format each element, ~^ means omit the inter-element stuff after the last element, and , means put that between elements. Of course , could be anything.
There are many variations on that; if that's not what you're looking for, maybe I can help you find it.
Suppose in a (wx)Maxima session I have the following
f:sin(x);
df:diff(f,x);
Now I want to have it output a text file containing something like, for example
If $f(x)=\sin(x)$, then $f^\prime(x)=\cos(x)$.
I found the tex and tex1 functions but I think I need some additional string processing to be able to do what I want.
Any help appreciated.
EDIT: Further clarifications.
Auto Multiple Choice is a software that helps you create and manage questionaires. To declare questions one may use LaTeX syntax. From AMC's documentation, a question looks like this:
\element{geographie}{
\begin{question}{Cameroon}
Which is the capital city of Cameroon?
\begin{choices}
\correctchoice{Yaoundé}
\wrongchoice{Douala}
\wrongchoice{Abou-Dabi}
\end{choices}
\end{question}
}
As can be seen, it is just LaTeX. Now, with a little modification, I can turn this example into a math question
\element{derivatives}{
\begin{question}{trig_fun_diff_1}
If $f(x)=\sin(x)$ then $f^\prime(0)$ is
\begin{choices}
\correctchoice{$1$}
\wrongchoice{$-1$}
\wrongchoice{$0$}
\end{choices}
\end{question}
}
This is the sort of output I want. I'll have, say, a list of functions then execute a loop calculating their derivatives and so on.
OK, in response to your updated question. My advice is to work with questions and answers as expressions -- build up your list of questions first, and then when you have the list in the structure that you want, then output the TeX file as the last step. It is generally much clearer and simpler to work with expressions than with strings.
E.g. Here is a simplistic approach. I'll use defstruct to define a structure so that I can refer to its parts by name.
defstruct (question (name, datum, item, correct, incorrect));
myq1 : new (question);
myq1#name : "trig_fun_diff_1";
myq1#datum : f(x) = sin(x);
myq1#item : 'at ('diff (f(x), x), x = 0);
myq1#correct : 1;
myq1#incorrect : [0, -1];
You can also write
myq1 : question ("trig_fun_diff_1", f(x) = sin(x),
'at ('diff (f(x), x), x = 0), 1, [0, -1]);
I don't know which form is more convenient for you.
Then you can make an output function similar to this:
tex_question (q, output_stream) :=
(printf (output_stream, "\\begin{question}{~a}~%", q#name),
printf (output_stream, "If $~a$, then $~a$ is:~%", tex1 (q#datum), tex1 (q#item)),
printf (output_stream, "\\begin{choices}~%"),
/* make a list comprising correct and incorrect here */
/* shuffle the list (see random_permutation) */
/* output each correct or incorrect here */
printf (output_stream, "\\end{choices}~%"),
printf (output_stream, "\\end{question}~%));
where output_stream is an output stream as returned by openw (which see).
It may take a little bit of trying different stuff to get derivatives to be output in just the format you want. My advice is to put the logic for that into the output function.
A side effect of working with expressions is that it is straightforward to output some representations other than TeX (e.g. plain text, XML, HTML). That might or might not become important for your project.
Well, tex is the TeX output function. It can be customized to some extent via texput (which see).
As to post-processing via string manipulation, I don't recommend it. However, if you want to go down that road, there are regex functions which you can access via load(sregex). Unfortunately it's not yet documented; see the comment header of sregex.lisp (somewhere in your Maxima installation) for examples.