how to do batch shorthand loop for large arrays? - arrays

hi I'm new to doing batch scripts so my code is simple.
I know you should use a for loop to iterate over an arrays contents but I saw a shorthand method that retrieves the contents with indexes between the specified range like so :
array[1-7]
and it works but when you use two digit numbers it runs into problems.
what am I doing wrong here?
appreciate your help :)

Related

Looping through a set of variables for R package analysis

Here's a novice question..being new to R this has got to be.
I am trying to run an R package that analyzes "csv" data using the following R scripts:
library(agricolae)
LXTOUTPUT2<-with(RLINXTES2, lineXtester(Replication, Lines, Tester, Y))
All elements analyzed by the function "lineXtester" are numerics.
Analyzing 1 variable is fine. However, I have several variables to supply as "Y" and would like to run this through as one chunk.
I tried the "for loop" but couldn't find the right script that would cycle thru all variables.
Instead of "for loop" is there a better, faster option? I read about "vectorizing" but R is still a strange stuff for me.
Would greatly appreciate your help.
Thank you.
My sincere apology. I was finally able to figure out my problem by reading and learning more about "vectorization" and applying it to my dataframe and accessing the elements using the [[]] indexing.
Indeed, it is much simpler and faster than using the "for loop".
Please disregard my request for help.
Thank you just the same.

Loop using variable that changes every loop-calculation with certain step-size

I am using a loop that adds a value (step) to dist. After adding step to dist I would like to use it in the following calculation which provides the value c. Both, dist and c, should then be listed in two columns next to each other in an output file.
If I use the code below it works at least to list the values for dist in the output file.
dist=0
do while (dist < rim)
dist=dist+step
c=0.5*(cl-cr)*erfc((dist)/(2*sqrt(t*d)))+cr
write(1,'(1f20.0)')dist*1E+06
enddo
If I replace the write command by the one below it will not list two nice columns but somehow mix both.
write(1,'(1f20.0,1f15.5)')dist*1E+06,c
Is this a problem related to the positioning of the writing command in the loop or is it related to the format it is told to write the values?
You should add a space between them and re-check:
write(*,'(F20.0,1X,F15.5)') dist*1E+06, c
Also consider the accuracy with which you are writing the results to the file.

zsh split directory into array

I'm trying to get an array containing the full current directory path in zsh. I'm currently using
local pwd="${PWD/#$HOME/~}"
pwd_list=(${(s:/:)pwd})
Which works except for one problem, it treats the starting / as a directory split too. I'd like my array to be like
/
usr
lib
php
instead of
usr
lib
php
I can see 2 ways of doing this but I'm unaware of how to do either in zsh. The first idea is to simple do a push and force a new element to the beginning (after the split).
The second, would be to alter the split to ignore the first / when parsing.
How can I resolve this to get an accurate directory path with minimal overhead into an array?
do you really need the first /? Assuming you're using a script to use the results of that, can't you just cd / to just start from there?
Anyways... is this what you want?
local pwd="${PWD/#$HOME/~}"
pwd_list=(${(s:/:)pwd})
pwd_list=('/' $pwd_list)
I think you're thinking about it slightly wrong. If you split "/usr/lib/php" on "/", you should get four elements, the first of which is an empty string. If you join those array elements back together with "/", you get the original path. Trying to think of the first element of "/" means you're treating the splitting inconsistently, which will make everything else harder.
So the problem really is that you're only getting three elements instead of four: the empty first element is getting dropped. You can fix that by quoting, like this:
local pwd="${PWD/#$HOME/~}"
pwd_list=( "${(s:/:)pwd}" )
(The extra space next to the outer parentheses isn't necessary, but it makes it a little easier to read.) You can even combine that into one expression:
pwd_list=( "${(s:/:)${PWD/#$HOME/~}}" )

Linux Bash pass function argument to array name

I'm working on a script that has a number of functions in place which pull data from a few different arrays. We hope to keep the arrays individualized for reporting purposes. The information in the arrays does not change and the only thing different between each function is which array name is being used. Since all of the functions have 98% the same content I'm trying to pull them into 1 single array for simplified management.
The issue I'm facing though is that I'm not able to figure out the correct syntax to obtain the length of an array based on the array title that is passed in the function argument. I can't post the actual script, but here is a mock up that details a simplified version of what I'm testing with. I believe if we can get it working using the mock script below I can transfer the needed changes to the actual script.
array1=(
"item1 123"
"item2 456"
)
array2=(
"stockA qwe"
"stockB asd"
"stockC zxc"
)
test() {
local ref=${1}[#]
IFS=$'\n'; for i in ${!ref}; do echo $i ; done
}
test array1
test array2
The script above so far will echo the content of each array line based on argument 1 when the function and it's argument is called; which is working as needed. I've tried many different combinations such as len=${#${1}[#]} but I always receive a "bad substitution" error. The functions I mention before have while loops and for statements that use the array length to know when to stop, so being able to pull that information really ties it all together. What I'm hoping for is something like the flow below
I plan to continue my research on this, but thank you for any help and knowledge that can be provided!
-Cyanide
I think the only solution is to create a copy of the array, then take the length of that array:
local ref=${1}[#]
copy=( "${!ref}" )
len=${#copy[#]}
Since bash does not allow chaining of the parameter expansion operators, I know of no shorter way to use both ${#...} and ${!...} on the same line.

Create functions in matlab

How can I create a function with MATLAB so I can call it any where in my code?
I'm new to MATLAB so I will write a PHP example of the code I want to write in MATLAB!
Function newmatlab(n){
n=n+1;
return n;
}
array=array('1','2','3','4');
foreach($array as $x){
$result[]=newmatlab($x);
}
print_f($result);
So in nutshell, I need to loop an array and apply a function to each item in this array.
Can some one show me the above function written in MATLAB so I can understand better?
Note: I need this because I wrote a code that analyzes a video file and then plots data on a graph. I then and save this graph into Excel and jpg. My problem is that I have more than 200 video to analyze, so I need to automate this code to loop inside folders and analyze each *.avi file inside and etc.
As others have said, the documentation covers this pretty thoroughly, but perhaps we can help you understand.
There are a handful of ways that you can define functions in Matlab, but probably the most useful for you to get started is to define one in an m-file. I'll use your example code. You can do this by creating a file called newmatlab.m in your project's directory that looks something like this
% newmatlab.m
function result = newmatlab(array)
result = array + 1
Note that the function has the same name as the file and that there is no explicit return statement - it figures that out by what you've named the output parameter(s) (result in this case).
Then, in the same directory, you can create a script (or another function) that calls your newmatlab function by that name:
% main.m (or whatever)
a = [1 2 3 4];
b = newmatlab(a)
That's it! This is a simplified explanation, but hopefully enough to get you started and then the documentation can help more.
PS: There's no "include" in Matlab; any functions that are defined in m-files in the current path are visible. You can find out what's in the path by using the path command. Roughly, it's going to consist of
Matlab's own directory
The MATLAB subdirectory of your Documents directory
The current working directory

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