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Pretty printing of matrices (and multidimensional arrays) #40

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certik opened this issue Dec 22, 2019 · 7 comments · May be fixed by #520
Open

Pretty printing of matrices (and multidimensional arrays) #40

certik opened this issue Dec 22, 2019 · 7 comments · May be fixed by #520
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easy Difficulty level is easy and good for starting into this project good first issue Good for newcomers in progress This proposal is being worked on topic: utilities containers, strings, files, OS/environment integration, unit testing, assertions, logging, ...

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@certik
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certik commented Dec 22, 2019

Currently the standard Fortran's print *, A prints a 2D array A as a 1D list of numbers. Rather, I would like stdlib to have a function print_array (we can discuss a better name) that would print the array as NumPy:

>>> numpy.arange(10000).reshape(250,40)
array([[   0,    1,    2, ...,   37,   38,   39],
       [  40,   41,   42, ...,   77,   78,   79],
       [  80,   81,   82, ...,  117,  118,  119],
       ..., 
       [9880, 9881, 9882, ..., 9917, 9918, 9919],
       [9920, 9921, 9922, ..., 9957, 9958, 9959],
       [9960, 9961, 9962, ..., 9997, 9998, 9999]])

or Julia:

julia> B = [1 2; 3 4; 5 6; 7 8; 9 10]
5×2 Array{Int64,2}:
 1   2
 3   4
 5   6
 7   8
 9  10

Julia can also use nice unicode characters for ... and vertical ... if the array is too large.

Then we should use this function at

stdlib/src/tests/loadtxt/test_loadtxt.f90

Line 21 in ae5591f

subroutine print_array(a)
and other places.

Then compilers can perhaps optionally use such print_array as default in the Fortran's language print statement.
@jvdp1
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jvdp1 commented Dec 22, 2019

My preference is for a format like Julia 's one. It would be also a similar format as savetxt.

@ivan-pi
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ivan-pi commented Dec 24, 2019

One prior art - Algorithm 892: DISPMODULE, a Fortran 95 module for pretty-printing matrices
https://dl.acm.org/citation.cfm?id=1486531

The code can be downloaded from netlib: http://netlib.org/toms/892.zip

@jvdp1
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jvdp1 commented Dec 24, 2019

One prior art - Algorithm 892: DISPMODULE, a Fortran 95 module for pretty-printing matrices
https://dl.acm.org/citation.cfm?id=1486531

The code can be downloaded from netlib: http://netlib.org/toms/892.zip

Thank you for mentioning this librabry. It seems to be quite complete and flexible. Could we use it (with some modernisations) in stdlib (license?)?

@ivan-pi
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ivan-pi commented Dec 25, 2019

Code published in TOMS is under the ACM Software License Agreement which allows usage for non-commercial purposes. I think that it is not compatible with what we want to achieve here.

I know Scipy contains the TOMS 748 algorithm. I checked and it looks like they wrote their own implementation.

@certik
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certik commented Dec 25, 2019 via email

@ivan-pi
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ivan-pi commented Dec 25, 2019

I had a look at the DISPMODULE API and it is indeed very nice and flexible supporting different formats (e.g. with a title, numbered rows and columns, precision, separators) and even printing several matrices adjacent to one another.

Taking a peak inside I can say that it would be beneficial to first start work on our own string module to handle conversion of reals/integers/logicals to character strings and some tools to parse format strings.

@jvdp1
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jvdp1 commented Dec 25, 2019

Taking a peak inside I can say that it would be beneficial to first start work on our own string module to handle conversion of reals/integers/logicals to character strings and some tools to parse format strings.

I agree with that. I would also add that I think it would be goood to first take a discussion on the issue #35 , because it will be the same problem for this issue #40 (i.e., printing matrices of different kinds).
Also, since we not use DISPMODULE, we could base this API on those of savetxt. Afterall, savetxt write a matrix to a file instead to the standard output.

@certik certik mentioned this issue Jan 2, 2020
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@jvdp1 jvdp1 added the topic: utilities containers, strings, files, OS/environment integration, unit testing, assertions, logging, ... label Jan 18, 2020
@milancurcic milancurcic added easy Difficulty level is easy and good for starting into this project good first issue Good for newcomers labels Mar 11, 2021
@awvwgk awvwgk linked a pull request Sep 18, 2021 that will close this issue
[stdlib_io] add disp(display variable values formatted). #520
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@zoziha zoziha linked a pull request Nov 9, 2021 that will close this issue
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@14NGiestas 14NGiestas added the in progress This proposal is being worked on label May 5, 2022
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[stdlib_io] add disp(display variable values formatted). zoziha/stdlib
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@certik @milancurcic @14NGiestas @jvdp1 @ivan-pi