numpy.recarray.itemset — NumPy v1.11 Manual (original) (raw)
recarray.itemset(*args)¶
Insert scalar into an array (scalar is cast to array’s dtype, if possible)
There must be at least 1 argument, and define the last argument as item. Then, a.itemset(*args) is equivalent to but faster than a[args] = item. The item should be a scalar value and _args_must select a single item in the array a.
| Parameters: | *args : Arguments If one argument: a scalar, only used in case a is of size 1. If two arguments: the last argument is the value to be set and must be a scalar, the first argument specifies a single array element location. It is either an int or a tuple. |
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Notes
Compared to indexing syntax, itemset provides some speed increase for placing a scalar into a particular location in an ndarray, if you must do this. However, generally this is discouraged: among other problems, it complicates the appearance of the code. Also, when using itemset (and item) inside a loop, be sure to assign the methods to a local variable to avoid the attribute look-up at each loop iteration.
Examples
x = np.random.randint(9, size=(3, 3)) x array([[3, 1, 7], [2, 8, 3], [8, 5, 3]]) x.itemset(4, 0) x.itemset((2, 2), 9) x array([[3, 1, 7], [2, 0, 3], [8, 5, 9]])