英文:
How to summarise data conditional on another variable in R?
问题
我想通过在另一列的值上进行条件计算，来总结数据，计算平均值。这里是一个例子：
dat <- data.frame(group = c("A", "A", "A", "A", "B", "B", "B", "B"),xy = c(1:4, 1:4),val = 1:8)
期望的输出是：
group var val1 A mean1_2 1.52 A mean3_4 3.53 B mean1_2 5.54 B mean3_4 7.5
我考虑过在dplyr中结合summarise和case_when，但这不起作用（或者我没有正确使用它）：
dat %>%group_by(group) %>%summarise(mean1_2 = case_when(xy %in% 1:2 ~ mean(val)),mean3_4 = case_when(xy %in% 3:4 ~ mean(val)))
有没有其他方法？我想避免将数据转换为宽格式。
英文:
I'd like to summarise data by calculating the mean of values in one column conditional on the values in another column. Here's an example:
dat <- data.frame(group = c("A", "A", "A", "A", "B", "B", "B", "B"),xy = c(1:4, 1:4),val = 1:8)> datgroup xy val1 A 1 12 A 2 23 A 3 34 A 4 45 B 1 56 B 2 67 B 3 78 B 4 8
The desired output is:
group var val1 A mean1_2 1.52 A mean3_4 3.53 B mean1_2 5.54 B mean3_4 7.5
I thought about combining summarise and case_when in dplyr but that does not work (or I've not used it correctly).
dat %>%group_by(group) %>%summarise(mean1_2 = case_when(xy %in% 1:2 ~ mean(val)),mean3_4 = case_when(xy %in% 3:4 ~ mean(val)))`summarise()` has grouped output by 'group'. You can override using the `.groups` argument.# A tibble: 8 x 3# Groups: group [2]group mean1_2 mean3_4<chr> <dbl> <dbl>1 A 2.5 NA2 A 2.5 NA3 A NA 2.54 A NA 2.55 B 6.5 NA6 B 6.5 NA7 B NA 6.58 B NA 6.5
Is there another way? I'd like to avoid spreading the data to wide format.
答案1
得分: 1
我不确定你的条件，但你可以尝试：
dat %>%mutate(key = ceiling(xy/2)) %>%group_by(group, key) %>%summarise(var = paste0(xy, collapse = "_"),val = mean(val)) %>%mutate(var = paste0('mean', var)) %>%select(-key)group var val<chr> <chr> <dbl>1 A mean1_2 1.52 A mean3_4 3.53 B mean1_2 5.54 B mean3_4 7.5
英文:
I'm not sure about your condition but you may try
dat %>%mutate(key = ceiling(xy/2)) %>%group_by(group, key) %>%summarise(var = paste0(xy, collapse = "_"),val = mean(val)) %>%mutate(var = paste0('mean',var)) %>%select(-key)group var val<chr> <chr> <dbl>1 A mean1_2 1.52 A mean3_4 3.53 B mean1_2 5.54 B mean3_4 7.5
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