Adding to an existing element in numpy array?

Question

How do you add one (+1) to a cell with an existing element in an numpy array? I have a 21x23 zeros array and I want to count occurences by adding one .

for r in holdscore:
    results = np.zeros(shape=(21, 23))
    if one_game(r) < 21:
        results[r,one_game(r)] += 1
    if one_game(r) > 21:
        results[r, 22] += 1

Don't really do numpy, but what you seem to be doing is that you are resetting results for every iteration. Try putting it outside the loop. — anon582847382
– anon582847382, Commented Apr 12, 2014 at 14:25

user2357112 · Accepted Answer · 2014-04-12 14:26:13Z

2

You're incrementing correctly. The problem is that you forget about the old array and make a new one every time through the loop.

Move this statement:

results = np.zeros(shape=(21, 23))

outside the loop:

results = np.zeros(shape=(21, 23))
for r in holdscore:
    if one_game(r) < 21:
        results[r,one_game(r)] += 1
    if one_game(r) > 21:
        results[r, 22] += 1

so it doesn't happen on every iteration.

answered Apr 12, 2014 at 14:26

user2357112

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1 Comment

anon582847382 Over a year ago

Damn, I was going to put this as an answer, but I wasn't sure. Glad someone else was though, +1.

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