Suppose I have a cell
v = 'v' [576.5818] [3.0286] [576.9270] 'v' [576.5953] [3.1180] [576.8716] 'f' [ 56] [ 58] [ 52] 'f' [ 56] [ 58] [ 52]
and I want to convert this to a cell array using a format string for each element:' %.5f'
How can I do this? I tried the following approach, but I get an error:
f1 = @(x) sprintf(' %.5f',x); cellfun(f1, num2cell(v),'UniformOutput', false)
I am getting an error as ???
Error using ==> sprintf
Function is not defined for 'cell' inputs.
Error in ==> @(x)sprintf(' %.5f',x)
Can any one help me thanks in advance
String is a cell array
Well, not really.. It is a matrix, but continue reading.
I guess cell array is the most mystic data type in MATLAB. So let's demystify it a bit ;-)
Assume
fruits = {... 'banana',... 'apple',... 'orange'... }
First of all integer indexing is not needed for small arrays. It is much better to use foreach-like constructions. Indeed,
for index = 1:numel(fruits) fruits{index} end
is equivalent to
for fruit = fruits fruit end
right?
Well, not quite. First loop produces strings, while the second one gives cells. You can check it with
for index = 1:numel(fruits) [isstr(fruits{index}) iscell(fruits{index})] end for fruit = fruits [isstr(fruit) iscell(fruit)] end
, i.e. [1 0] and [0 1].
If you have spot the difference, then you must know what to do with the next example (in this one is really relate to your question (!) I promise!). Say you try to do horizontal concatenation in a loop:
for fruit = fruits [fruit 'is a fruit'] end
You will get
ans = 'banana' 'is a fruit'
and so on. Why? Apparently this code tries to concatenate a nested cell array to a string (a cell array containing a matrix of chars which constitute the string like 'banana'). So, correct answer is
Use {:}
for fruit = fruits [fruit{:} 'is a fruit'] end
Magically this already produces the expected 'banana is a fruit', 'apple is a fruit', etc.
Hints
A few hints:
- Index-free looping works nicely with structs as in
for fruit = [fieldnames][1](fruits)' - The above is true for open source octave
- banana is not just fruit, taxonomically it is also a herb ;-) just like 'banana' in MATLAB is both a string and a matrix, i.e. assert(isstr('banana') && ismat('banana')) passes, but assert(iscell('banana')) fails.
{:} is equivalent to cell2mat
PS
a solution to your question may look like this:
Given
vcell = {... 'v' 576.5818 3.0286 576.9270; 'v' 576.5818 3.0286 576.9270 }
covert index-wise only numeric types to strings
vcell(cellfun(@isnumeric, vcell)) = cellfun(@(x) sprintf('%.5f', x), vcell(cellfun(@isnumeric, vcell)), 'UniformOutput', false)
Above code outputs
vcell =
'v' '576.58180' '3.02860' '576.92700' 'v' '576.58180' '3.02860' '576.92700'
which can be concatenated.
Suppose we have a cell as follows:
my_cell = {'Hello World'} class(my_cell) ans = cell
We can get the string out of it simply by using the {:} operator on it directly.
class(my_cell{:}) ans = char
Note that we can use the expression mycell{:} anywhere we would use a normal string.
Try this:
sprintf(' %.5f',x{:})
(Works according to some Google results.)
By looking in the strjoin.m file i found this:
string = [x{:}];
