How to select non-string variables convertvars( ) argument?

Question

Simon 2024-1-31

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2076721-how-to-select-non-string-variables-convertvars-argument

评论： Simon 2024-2-4

I want to convert non-string variables to string using convertvars. I can do convertvars(T, @isnumeric, 'string') and convertvars(T, @iscell, 'string'). When I want to convert all variables to string, that approach would be cumbersome. I have tried ~@isstring. That is of course a rediculous and wrong idea. Is there a way to select non-string variables from a table?

c = {1,2,3;'a','b','c'; "d", "e", "f"}'
c = 3×3 cell array
    {[1]}    {'a'}    {["d"]}
    {[2]}    {'b'}    {["e"]}
    {[3]}    {'c'}    {["f"]}
t = cell2table(c)
t = 3×3 table
    c1     c2      c3 
    __    _____    ___

    1     {'a'}    "d"
    2     {'b'}    "e"
    3     {'c'}    "f"
convertvars(t, @isnumeric, 'string') % convert one column at a time
ans = 3×3 table
    c1      c2      c3 
    ___    _____    ___

    "1"    {'a'}    "d"
    "2"    {'b'}    "e"
    "3"    {'c'}    "f"
convertvars(t, 1:width(t), 'string') % works but I like to see a better solution
ans = 3×3 table
    c1     c2     c3 
    ___    ___    ___

    "1"    "a"    "d"
    "2"    "b"    "e"
    "3"    "c"    "f"

2 个评论
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Mathieu NOE 2024-1-31

在 MATLAB Online 中打开

why is

convertvars(t, 1:width(t), 'string') % works but I like to see a better solution

not a good solution in your eyes ?

Simon 2024-2-4

在 MATLAB Online 中打开

load patients.mat
t=table(Age, Location, LastName, Gender, Height);

This solution is slower because it converts string to string reduntly.

tic
convertvars(t, 1:width(t), 'string');
toc
Elapsed time is 0.016945 seconds.

Much faster solution

tic 
convertvars(t, @(x)~isstring(x), 'string');
toc
Elapsed time is 0.004329 seconds.

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Answer 1

Voss 2024-1-31

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2076721-how-to-select-non-string-variables-convertvars-argument#answer_1400606

在 MATLAB Online 中打开

c = {1,2,3;'a','b','c'; "d", "e", "f"}'
c = 3×3 cell array
    {[1]}    {'a'}    {["d"]}
    {[2]}    {'b'}    {["e"]}
    {[3]}    {'c'}    {["f"]}
t = cell2table(c)
t = 3×3 table
    c1     c2      c3 
    __    _____    ___

    1     {'a'}    "d"
    2     {'b'}    "e"
    3     {'c'}    "f"
convertvars(t, @(x)~isstring(x), 'string')
ans = 3×3 table
    c1     c2     c3 
    ___    ___    ___

    "1"    "a"    "d"
    "2"    "b"    "e"
    "3"    "c"    "f"