std

std(X)

If X is a vector, return the (unbiased) sample standard deviation of X.

If X is a matrix, calculate the (unbiased) sample standard deviation of each column of X and return a vector.

If X is a table, calculate the (unbiased) sample standard deviation of each column of X and return a table.

As with all aggregate functions, null values are not included in the calculation.

Difference from Python’s numpy.std: numpy.std calculates the population standard deviation by default (ddof=0). DolphinDB’s std returns the unbiased sample standard deviation, equivalent to ddof=1. DolphinDB also ignores NULL values and calculates column-wise for matrices and tables.

X is a scalar/vector/matrix/table.

A scalar, vector, or table.

std(1 2 3);
// output: 1

m=matrix(1 3 5 7 9, 1 4 7 10 13);
m;

std(m);
// output: [3.162277660168379,4.743416490252569]