How to split a number into 5 parts equalling the sum of the number

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So i am trying to create a code that reads a large CSV that:
  • counts the rows
  • divides the rows by 5
  • create an array that stores these parts [1 1part 2part 3part 4part 5part]
  • create a new csv'
So read a csv and split it into 5 parts.
The idea i had was splitNum = rowcount/5 and then splitArray = [1:rowcount:totalrows] and then loop the table with this array until done
but ofcourse this doesnt equal the total number of rows properly.
What would be a better solution for this?

Answers (2)

Jon on 10 Mar 2022
Not sure exactly what you are expecting, but obviously if your total number of rows is not a multiple of 5 then you cannot split your original file into 5 files with equal number of rows.
If you want you could have all but the last file have the same number of rows using
n = floor(totalrows/5)
split = 1:n:totalrows
So for example if totalrows = 23, then you would have 5 files, each with 4 rows and then the last one would have only 3.
  1 Comment
MKM on 11 Mar 2022
Yep exactly, i managed to solve the problem in the end with the similar way you thought out here. I count the total rows in the main CSV (say 220000) divided that by a total number of rows i want each individual CSV to have(say 50000). This give me the count of how many files i would have. (floor(220000/5)) =4
after i have this number i itterate 3 files with 50000 rows (150000). once it reaches the last count (file 4) i use end to get the next 50000 + anything after (20000) this gives me 3 files with 50000 rows and 1 files with a little bit extra.

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Walter Roberson
Walter Roberson on 11 Mar 2022
CSV = readmatrix(filename) ;
R = size(CSV, 1);
N = floor(R/5);
parts = mat2cell(CSV, [N, N, N, N, R-4*N],size(CSV, 2));
Now write out parts{1} to 5
The last part might be up to 4 samples larger.


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