Count orders by payment channel

Question

You receive orders as a list of dictionaries and need a quick channel mix breakdown for the daily standup.

Write a function `count_by_channel(orders)` that returns a dictionary mapping each `channel` value to the number of orders that used it.

Accepted Answer

Step 1: Start with an empty dictionary that will hold one entry per channel. Step 2: Loop the orders and read `order["channel"]` — the grouping key. Step 3: `counts.get(channel, 0) + 1` reads the running count, defaulting to `0` the first time a channel appears, so there is no `KeyError`. Step 4: Return the dictionary. `collections.Counter([o["channel"] for o in orders])` is the one-line equivalent interviewers like to see as a follow-up.

Count orders by payment channel

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