Free toolドラ
Dora danger vs riichi
A riichi just went up and you hold the dora. Pick the tile. You get how often a tenpai hand waits on it, next to the odds for a plain tile.
Deal-in danger
Riichi, it's the dora, 5:
11.5%of riichi hands wait on a 5 dora
Based on 23,959 riichi hands with that dora.
1.4×the danger of a plain 5 (8.0%), complex waits left out on both sides.
- Against
- Riichi
- Your tile
- It's the dora
- Tile
- 5
How to use this
- Pick riichi or open hand.
- Say how your tile relates to the dora: it is the dora, it sits next to it, or it's an ordinary tile.
- Pick the tile. Next to the dora, pick the dora's number instead: the data counts waits around it as one zone.
What the number counts
- The share is how often a tenpai hand waits on that tile. Throw it right after the riichi, before any other read, and that's your deal-in chance.
- The multiple compares the dora with the same tile when it isn't dora. Complex waits are left out of both sides, because the plain-tile numbers leave them out.
- Next to the dora, the factors compare waits around the dora with the same waits around a plain tile. Treat them as relative danger, not as odds for one tile.
- Only the first dora counts. Kan dora and red fives aren't in it, and nobody checked for furiten.
Where the numbers come from
Tenhou Houou logs 2016–2020, analysis by chienshyong (fork of Euophrys/houou-analysis)
Dora numbers come from DorasobaDanger.csv: 273,951 riichi hands, read when the riichi is accepted, and 357,644 open hands, read at the first cut from hand that leaves them tenpai. Plain-tile numbers come from WaitDistribution.csv, a separate run of 142,461 riichi hands and 182,490 open hands. The two samples differ, so read the multiples as rough.
No neighbour factors for a 1 or 9 dora: the analysis lets a few waits from the next suit into that count. Honors only have numbers as the dora, because the plain-tile run doesn't split honors by copies out.
The original analysis code is Euophrys/houou-analysis. The tool reads the published result tables as they stand and does the division itself.
These numbers are statistical guidance for Houou-level 4-player hanchan. Your table, the scores and your reads can make a different play right.
Want a pro to check your real hands?
The table gives the average danger of a tile. A review shows when you held the dora too long, cut it too early or pushed it into a riichi. Send me a log and I'll mark those hands.
Keep sharpening
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