2
$\begingroup$

I want to write lists of expressions into an output file with names assigned to each list. Later I want to import them in a new notebook for further use.

Example.

list1={{a^2,b^2},{a+b,a^3},{a-b,b^3}};
list2={{c^2,d^2},{c+d,c^3},{d-c,d^3}};

I want to export them to a single file.

Open["out.dat"]
Export["out.dat",{list1,list2},"Text"]
Close["out.dat"]

which results:

cat out.dat
{{a^2, b^2}, {a + b, a^3}, {a - b, b^3}}
{{c^2, d^2}, {c + d, c^3}, {-c + d, d^3}}

Now to import them in a new notebook:

input=Import["out.dat","Text"];
list1=input[[1]];
list2=input[[2]];

Rather a convenient approach would be to save the (preferably customized) names of the lists as well. The option I found is using Save :

Save["out1.dat",{list1,list2}];

which results in

**cat out1.dat**
list1 = {{a^2, b^2}, {a + b, a^3}, {a - b, b^3}}
list2 = {{c^2, d^2}, {c + d, c^3}, {-c + d, d^3}}

This is precisely what I wanted. However, there is one exception. Assume that the original names of the lists are not as simple as list1,list2 but something like

 list["MyList"<>"1"]={{a^2,b^2},{a+b,a^3},{a-b,b^3}};
 list["MyList"<>"2"]={{c^2,d^2},{c+d,c^3},{d-c,d^3}};

Here Save does not work as before as it needs only symbols and strings. This is where I need some help:

How do I save these types of names in a file with the Lists assigned to it?

In this case, the expected output would be

 cat out.dat
 list["MyList1"]={{a^2,b^2},{a+b,a^3},{a-b,b^3}};
 list["MyList2"]={{c^2,d^2},{c+d,c^3},{d-c,d^3}};

Is there any way to achieve this?


EDIT: I realized that Save can be used in this case as well.

Save["out.dat",list]

will give the output as

 list["MyList1"]={{a^2,b^2},{a+b,a^3},{a-b,b^3}}
 list["MyList2"]={{c^2,d^2},{c+d,c^3},{d-c,d^3}}

However, in this case, it writes ALL occurrences of list[_ _ _]. This is therefore not as flexible as one wants it to be.

$\endgroup$
1
  • $\begingroup$ Well, I just realized that Save can also handle this. Apparently Save["out.dat",list] will save the functions with the names although without the last ";" But its fine I think. In any case I would appreciate if any alternative approach is out there. $\endgroup$
    – BabaYaga
    Oct 2, 2023 at 11:42

1 Answer 1

0
$\begingroup$

As pointed Save["out.dat",list] could be a suboptimal solution. However, this has drawbacks in that it does not provide flexibility and tries to write every function in the output file.

A better approach would be to use Export along the following line:

 Export["out.dat",
        {"list[\"MyList"<>"1\"] = ", list["MyList"<>"1"], ";",
         "list[\"MyList"<>"2\"] = ", list["MyList"<>"2"], ";"}, "List"];

The result is very close to the expected output (except the line breaks):

cat out.dat

list["MyList1"] =
{{a^2, b^2}, {a + b, a^3}, {a - b, b^3}}
;
list["MyList2"] =
{{c^2, d^2}, {c + d, c^3}, {-c + d, d^3}}
;
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.