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What does it mean in MATLAB when I do:
array = array (1:number)
and what does it mean:
array = array(indexes_array)
and finally, what does it mean:
array = array(indexes_array,:)
Answers, according to MATLAB docs:
1)
array = array (1:number)
The colon notation in MATLAB provides an easy way to extract a range of elements from v:
v(3:7) % Extract the third through the seventh elements
ans =
9 4 2 11 7
2)
array = array(indexes_array)
array is reorganized according to indexes_array order, assuming that indexes_array is composed of indexes.
3)
array = array(indexes_array,:)
just the same as number 1), array is reorganized according to all the rows of indexes_array, ignoring the columns.
References:
https://www.mathworks.com/help/matlab/math/array-indexing.html
https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html
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How do I swap an(example) array's second and third elements? I tried the following
def swap_elements(array)
array = ["blake", "ashley", "scott"]
array[1], array[2] = array[2], array[1]
end
but I get
: ["scott", "ashley"]
I lost the first[0] element
There are many ways to do this - this is a functional approach that doesn't mutate the original array:
def swap_elements(array)
# yields the array to the block
array.then do |first, *rest| # deconstruct the array
rest.reverse # swap the places of 2 & 3
.unshift(first) # put the first back in
end
end
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Language of odd length and cannot contain length multiple of 3 over
𝚺={𝒂,𝒃}
OK to have an odd length that's not a multiple of 3, we can have a "head" part that generates strings of length 6n, and then a "tail" part that generates strings of length 1 and 5 (but not 7). Any odd number that's not a multiple of 3 can be written as 6n + 1 or 6n + 5 for n >= 0. So, let's get crackin.
r = ((a + b)^6)*((a + b) + (a + b)^5)
I have used a shorthand notation here which you can omit; basically, s ^ n stands for the regular expression s repeated n times. As long as n is a definite number this can be written out, just makes the regular expression a little longer.
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I have 2 arrays like and , I want to generate a new array with 2 elements like pID and cNo. pID is getting from the first array and the cNO is from the second array. How to merge these 2 arrays like
newarr= { 0: pID:970989, cID:'dfds'
1: pID:970995, cID:'fgd',
2: pID:971006, cID:'t765'}
Assuming your arrays are equal in length you can just loop over one of them and create a new array.
const newArray = pIDArray.map((pID, index) => ({ pID, CID: cIDArray[index] }));
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I have 2 arrays of strings as under. I want to compare them and execute some code if these arrays are not equal-
current_instances = ["170601_7711", "170601_8811"]
app_instances = ["170602_7711", "170602_8811"]
How can I compare them in ruby?
x = ["alpha1", "beta1"]
y = ["alpha2", "beta2"]
Check if all elements are the same
x == y #=> false
Compare each element
Compare each string at some index i, assuming both arrays are the same size. Then apply some code to the matches.
x.zip(y) #=> [["alpha1", "alpha2"], ["beta1", "beta2"]]
x.zip(y).map {|a,b| a == b ? 'do this' : 'else do this' }
#=> ["else do this", "else do this"]
Perhaps you can do an array difference with the - operator and execute your code if the difference is zero
arr_diff = current_instances - app_instances
This is the simplest solution I could think of :)
Check my solution and let me know how it goes
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What i want to do,is print random elements from array,heres example code:
myTable = { "one", "two", "three","four"}
-- print here: one,three,four
Printing random element is simple -- print(myTable[math.random(#myTable)]) -- but if you need to make each printed element unique, then you better shuffle the elements in the array and print the resulting elements one-by-one. You may check this SO answer for ideas.
If you want N amount of elements, you need to make use of a loop:
local myTable = { "one", "two", "three","four"}
local result = {}
for i=1,3 do -- N here, e.g 3 if you want 3 elements
result[i] = table.remove(myTable,math.random(#myTable))
end
print(table.concat(result,", "))
-- "four, two, three" as an example
The code will error if you request more elements than there are in the table. If you want to reuse the table later on, you'll have to copy it, as this code actually removes elements from the table.