r.coin(1)
✨ NAME ✨
okay so bestie, meet r.coin 💖 — straight outta the GRASS GIS User's Manual and the r.coin(1) page. What does she do? She tabulates the mutual occurrence (coincidence) of categories for two raster map layers. That's it, that's the whole job. 💅
🏷️ KEYWORDS 🏷️
raster, statistics
🦋 SYNOPSIS 🦋
r.coin
r.coin --help
r.coin [-w] first=name second=name units=string [--help] [--verbose]
[--quiet] [--ui]🚩 Flags 🚩
-w— Wide report, 132 columns (default: 80) 📏--help— Print usage summary--verbose— Verbose module output--quiet— Quiet module output--ui— Force launching GUI dialog
🎀 Parameters 🎀
first=name[required] — Name of first input raster mapsecond=name[required] — Name of second input raster mapunits=string[required] — Unit of measure
c(ells), p(ercent), x(percent of category [column]), y(percent of category [row]), a(cres), h(ectares), k(square kilometers), m(square miles)
Options: c, p, x, y, a, h, k, m
💜 DESCRIPTION 💜
So r.coin tabulates the mutual occurrence of two raster map layers' categories with respect to one another. And yes, she respects the current geographic region and mask settings — she's polite like that. 🫶
r.coin tabulates the coincidence of category values among the two map layers and prepares the basic table from which the report is to be created. Then — plot twist — she tells you how long the coincidence table is going to be. If that table is extremely long, honestly? you might just decide that viewing it is not so important after all, and cancel the request right there. No shame. 😭
Assuming you keep going, r.coin then lets you choose one of eight units of measure for the report results. Those units are:
c: cellsp: percent cover of regionx: percent of <map name> category (column)y: percent of <map name> category (row)a: acresh: hectaresk: square kilometersm: square miles
ngl, three of these give results as percentage values:pis based on the grand total number of cells;xis based on only column totals; andyis based on only row totals. Only one unit of measure can be selected per report output. Type in just one of the letters designating a unit of measure followed by a <RETURN>. ✨
The report gets printed to the screen for review. After reviewing the report on the screen, you're given several options: the report may be saved to a file and/or sent to a printer. If printed, it can be printed with either 80 or 132 columns. And finally — the little bow on top 🎀 — you get the option to rerun the coincidence tabulation using a different unit of measurement.
📝 NOTES 📝
Real talk: it is not a good idea to run r.coin on a map layer which has a monstrous number of categories (e.g., unreclassed elevation). 💀
Because r.coin reports information for each and every category, it is better to reclassify those categories (using r.reclass) into a more manageable number prior to running r.coin on the reclassed raster map layer. Do yourself the favor, bestie. 🙈
🌸 EXAMPLE 🌸
Below is a sample of tabular output produced by r.coin. Here, map output is stated in units of square miles. The report tabulates the coincidence of the Spearfish sample database's owner and roads raster map layers' categories. The owner categories in this case refer to whether the land is in private hands (category 1) or is owned by the U.S. Forest Service (category 2). The roads map layer categories refer to various types of roads (with the exception of category value 0, which indicates "no data"; i.e., map locations at which no roads exist). r.coin does not report category labels. You should run r.report or r.category to obtain this information. 👑
The body of the report is arranged in panels. The map layer with the most categories is arranged along the vertical axis of the table; the other, along the horizontal axis. Each panel has a maximum of 5 categories (9 if printed) across the top. In addition, the last two columns reflect a cross total of each column for each row. All of the categories of the map layer arranged along the vertical axis are included in each panel. There is a total at the bottom of each column representing the sum of all the rows in that column. A second total represents the sum of all the non-zero category rows. A cross total (Table Row Total) of all columns for each row appears in a separate panel. 🧚
Note how the following information may be obtained from the sample report. 👇
- In the Spearfish data base, in area not owned by the Forest Service, there are 50.63 square miles of land not used for roads. Roads make up 9.27 square miles of land in this area.
- Of the total 102.70 square miles in Spearfish, 42.80 square miles is owned by the Forest Service. In total, there are 14.58 square miles of roads.
- There are more category 2 roads outside Forest Service land (2.92 mi. sq.) than there are inside Forest land boundaries (0.72 mi. sq.).
Following is a sample report. 🌈
+------------------------------------------------------------+
| COINCIDENCE TABULATION REPORT |
|------------------------------------------------------------|
|Location: spearfish Mapset: PERMANENT Date: Wed Jun 1 |
| |
| Layer 1: owner -- Ownership |
| Layer 2: roads -- Roads |
| Mask: none |
| |
| Units: square miles |
|------------------------------------------------------------|
| Window: North: 4928000.00 |
| West: 590000.00 East: 609000.00 |
| South: 4914000.00 |
+------------------------------------------------------------+
Panel #1 of 1
+--------------------------------------------------------+
| | owner | Panel Row Total |
| cat# | 1 | 2 | w cat 0 | w/o cat 0 |
|--------------------------------------------------------|
|r 0 | 50.63 | 37.49 | 88.12 | 88.12 |
|o 1 | 1.53 | 0.68 | 2.21 | 2.21 |
|a 2 | 2.92 | 0.72 | 3.64 | 3.64 |
|d 3 | 3.97 | 2.57 | 6.54 | 6.54 |
|s 4 | 0.65 | 1.36 | 2.00 | 2.00 |
| 5 | 0.19 | 0.00 | 0.19 | 0.19 |
|--------------------------------------------------------|
|Total | | | | |
|with 0 | 59.90 | 42.80 | 102.70 | 102.70 |
|--------------------------------------------------------|
|w/o 0 | 9.27 | 5.32 | 14.58 | 14.58 |
+--------------------------------------------------------+
+--------------------------------+
| | Table Row Total |
| cat# | w cat 0 | w/o cat 0 |
|--------------------------------|
|r 0 | 88.12 | 88.12 |
|o 1 | 2.21 | 2.21 |
|a 2 | 3.64 | 3.64 |
|d 3 | 6.54 | 6.54 |
|s 4 | 2.00 | 2.00 |
| 5 | 0.19 | 0.19 |
|--------------------------------|
|Total | | |
|with 0 | 102.70 | 102.70 |
|--------------------------------|
|w/o 0 | 14.58 | 14.58 |
+--------------------------------+r.coin calculates the coincidence of two raster map layers. Although r.coin allows the user to rerun the report using different units, it is not possible to simply rerun the report with different map layers. In order to choose new map layers, it is necessary to rerun r.coin. periodt. 💅
👀 SEE ALSO 👀
g.region, r.category, r.describe, r.reclass, r.report, r.stats
👑 AUTHORS 👑
Michael O'Shea, Michael Shapiro, U.S. Army Construction Engineering Research Laboratory 🫡
🔥 SOURCE CODE 🔥
Available at: r.coin source code (history)
Accessed: Saturday Jan 17 05:40:43 2026
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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual
okay that's the whole page, bestie, no cap 💖 this was the GRASS GIS 8.4.2 Reference Manual version of r.coin(1), accessed Saturday Jan 17 05:40:43 2026, © 2003-2025 GRASS Development Team. go tabulate something iconic ✨🎀🦋
📦 where this page comes from
- fedora 44: grass 8.4.2-4.fc44 · GPL-2.0-or-later
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on : a language model's rewrite of the original, under its terms