我有一个带有字符串列的数据框，我需要将所有相等的值压缩成一个值。我的数据集的一个例子：
CommonName Month Site season period
23 Gambel's Quail Oct McDowell Sonoran Preserve Autumn 4
24 American Kestrel Nov McDowell Sonoran Preserve Autumn 4
25 Black-throated Sparrow Nov McDowell Sonoran Preserve Autumn 4
26 Brewer's Sparrow Nov McDowell Sonoran Preserve Autumn 4
27 Common Raven Nov McDowell Sonoran Preserve Autumn 4
28 Gilded Flicker Nov McDowell Sonoran Preserve Autumn 4
29 Loggerhead Shrike Nov McDowell Sonoran Preserve Autumn 4
30 Loggerhead Shrike Nov McDowell Sonoran Preserve Autumn 4
31 Northern Mockingbird Nov McDowell Sonoran Preserve Autumn 4
32 Red-tailed Hawk Nov McDowell Sonoran Preserve Autumn 4
33 White-crowned Sparrow Nov McDowell Sonoran Preserve Autumn 4
107 Acorn Woodpecker Oct McDowell Sonoran Preserve Autumn 4
108 Say's Phoebe Nov McDowell Sonoran Preserve Autumn 4
236 Abert's Towhee Nov Brown's Ranch Wash Autumn 4
237 Cactus Wren Nov Brown's Ranch Wash Autumn 4
238 Canyon Towhee Nov Brown's Ranch Wash Autumn 4
239 Curve-billed Thrasher Nov Brown's Ranch Wash Autumn 4
240 Gambel's Quail Nov Brown's Ranch Wash Autumn 4
此数据跨越多年，因此物种可能会多次列出。这是我想避免的，因为我只想确定每个地点和季节内物种的出现。所以在这个例子中，我想只为Loggerhead Shrike和Gambel的Quail提供一个数据点，而其他一切都保持不变。我感谢您的帮助。我一直没有找到类似的问题，但我不确切地知道这个过程会被称为什么。
答案 0 :(得分：0)
To＆＃34;为确定每个地点和季节内物种的发生情况，请尝试以下方法：
> with(ddf, table(CommonName, Site, Season))
, , Season = Autumn
Site
CommonName BrownsRanch McDowell
Aberts Towhee 1 0
Acorn Woodpecker 0 1
American Kestrel 0 1
Black-throated Sparrow 0 1
Brewers Sparrow 0 1
Cactus Wren 1 0
Canyon Towhee 1 0
Common Raven 0 1
Curve-billed Thrasher 1 0
Gambels Quail 1 1
Gilded Flicker 0 1
Loggerhead Shrike 0 2
Northern Mockingbird 0 1
Red-tailed Hawk 0 1
Says Phoebe 0 1
White-crowned Sparrow 0 1
或者：
> with(ddf, table(CommonName, Season, Site))
, , Site = BrownsRanch
Season
CommonName Autumn
Aberts Towhee 1
Acorn Woodpecker 0
American Kestrel 0
Black-throated Sparrow 0
Brewers Sparrow 0
Cactus Wren 1
Canyon Towhee 1
Common Raven 0
Curve-billed Thrasher 1
Gambels Quail 1
Gilded Flicker 0
Loggerhead Shrike 0
Northern Mockingbird 0
Red-tailed Hawk 0
Says Phoebe 0
White-crowned Sparrow 0
, , Site = McDowell
Season
CommonName Autumn
Aberts Towhee 0
Acorn Woodpecker 1
American Kestrel 1
Black-throated Sparrow 1
Brewers Sparrow 1
Cactus Wren 0
Canyon Towhee 0
Common Raven 1
Curve-billed Thrasher 0
Gambels Quail 1
Gilded Flicker 1
Loggerhead Shrike 2
Northern Mockingbird 1
Red-tailed Hawk 1
Says Phoebe 1
White-crowned Sparrow 1
我将一些季节作品更改为春季：
> with(ddf, table(CommonName, Season, Site))
, , Site = BrownsRanch
Season
CommonName Autumn Spring
Aberts Towhee 0 1
Acorn Woodpecker 0 0
American Kestrel 0 0
Black-throated Sparrow 0 0
Brewers Sparrow 0 0
Cactus Wren 0 1
Canyon Towhee 1 0
Common Raven 0 0
Curve-billed Thrasher 1 0
Gambels Quail 1 0
Gilded Flicker 0 0
Loggerhead Shrike 0 0
Northern Mockingbird 0 0
Red-tailed Hawk 0 0
Says Phoebe 0 0
White-crowned Sparrow 0 0
, , Site = McDowell
Season
CommonName Autumn Spring
Aberts Towhee 0 0
Acorn Woodpecker 0 1
American Kestrel 1 0
Black-throated Sparrow 1 0
Brewers Sparrow 1 0
Cactus Wren 0 0
Canyon Towhee 0 0
Common Raven 1 0
Curve-billed Thrasher 0 0
Gambels Quail 1 0
Gilded Flicker 1 0
Loggerhead Shrike 0 2
Northern Mockingbird 0 1
Red-tailed Hawk 0 1
Says Phoebe 0 1
White-crowned Sparrow 0 1
删除名称，地点和季节相同的额外行：
> ddf[!duplicated(paste(ddf$CommonName,ddf$Site,ddf$Season)),]
CommonName Month Site Season period
1 Gambels Quail Oct McDowell Autumn 4
2 American Kestrel Nov McDowell Autumn 4
3 Black-throated Sparrow Nov McDowell Autumn 4
4 Brewers Sparrow Nov McDowell Autumn 4
5 Common Raven Nov McDowell Autumn 4
6 Gilded Flicker Nov McDowell Autumn 4
7 Loggerhead Shrike Nov McDowell Autumn 4
9 Northern Mockingbird Nov McDowell Autumn 4
10 Red-tailed Hawk Nov McDowell Autumn 4
11 White-crowned Sparrow Nov McDowell Autumn 4
12 Acorn Woodpecker Oct McDowell Autumn 4
13 Says Phoebe Nov McDowell Autumn 4
14 Aberts Towhee Nov BrownsRanch Autumn 4
15 Cactus Wren Nov BrownsRanch Autumn 4
16 Canyon Towhee Nov BrownsRanch Autumn 4
17 Curve-billed Thrasher Nov BrownsRanch Autumn 4
18 Gambels Quail Nov BrownsRanch Autumn 4
请注意，引号（如Gambel＆＃39; s）在字符串条目中表现不佳，并已从上述数据中删除。