r - 如何在来自两个数据帧的分组值之间执行操作

Question

我有两个数据框:

src_tbl <- structure(list(Sample_name = c("S1", "S2", "S1", "S2", "S1", 
"S2"), crt = c(0.079, 0.082, 0.079, 0.082, 0.079, 0.082), sr = c(0.592, 
0.549, 0.592, 0.549, 0.592, 0.549), condition = c("x1", "x1", 
"x2", "x2", "x3", "x3"), score = c("0.077", "0.075", "0.483", 
"0.268", "0.555", "0.120")), row.names = c(NA, -6L), .Names = c("Sample_name", 
"crt", "sr", "condition", "score"), class = c("tbl_df", 
"tbl", "data.frame"))
src_tbl
#>   Sample_name   crt    sr condition score
#> 1          S1 0.079 0.592        x1 0.077
#> 2          S2 0.082 0.549        x1 0.075
#> 3          S1 0.079 0.592        x2 0.483
#> 4          S2 0.082 0.549        x2 0.268
#> 5          S1 0.079 0.592        x3 0.555
#> 6          S2 0.082 0.549        x3 0.120

ref_tbl <- structure(list(Sample_name = c("P1", "P2", "P3", "P1", "P2", 
"P3", "P1", "P2", "P3"), crt = c(1, 1, 1, 1, 1, 1, 1, 1, 1), 
    sr = c(2, 2, 2, 2, 2, 2, 2, 2, 2), condition = c("r1", "r1", 
    "r1", "r2", "r2", "r2", "r3", "r3", "r3"), score = c("0.200", 
    "0.201", "0.199", "0.200", "0.202", "0.200", "0.200", "0.204", 
    "0.197")), row.names = c(NA, -9L), .Names = c("Sample_name", 
"crt", "sr", "condition", "score"), class = c("tbl_df", 
"tbl", "data.frame"))
ref_tbl
#>   Sample_name crt sr condition score
#> 1          P1   1  2        r1 0.200
#> 2          P2   1  2        r1 0.201
#> 3          P3   1  2        r1 0.199
#> 4          P1   1  2        r2 0.200
#> 5          P2   1  2        r2 0.202
#> 6          P3   1  2        r2 0.200
#> 7          P1   1  2        r3 0.200
#> 8          P2   1  2        r3 0.204
#> 9          P3   1  2        r3 0.197

我想要做的是在 ks.test() 上执行操作( score )按 Sample_name 分组的列在两个数据框中。例如，S1 和 P1 的 KS 检验的 p 值为:

# in src_tbl
s1 <- c(0.077,0.483,0.555)
#in ref_tbl
p1 <- c(0.200,0.200,0.200)
testout <- ks.test(s1,p1)
#> Warning in ks.test(s1, p1): cannot compute exact p-value with ties
broom::tidy(testout)
#>   statistic   p.value                             method alternative
#> 1 0.6666667 0.5175508 Two-sample Kolmogorov-Smirnov test   two-sided

我想要做的是对所有操作执行所有操作，以便最终得到这样的表

src  ref   p.value
S1   P1    0.5175508
S1   P2    0.6
S1   P3    0.6
S2   P1    0.5175508
S2   P2    0.6
S2   P3    0.6

我怎样才能做到这一点？最好快，因为 ref_table 中的样本数可能很大(P1，P2 .... P10k)。

Answer 1

这是 tidyverse 中的解决方案.我首先将分数嵌套在每个源数据集中:

ref_tbl <- ref_tbl %>% 
  mutate(ref = as.factor(Sample_name),
         score_ref = as.numeric(score)) %>%
  select(ref, score_ref) %>%
  tidyr::nest(score_ref)

ref_tbl
# A tibble: 3 x 2
     ref                    data
  <fctr>                  <list>
1     P1 <tibble [3 x 1]>
2     P2 <tibble [3 x 1]>
3     P3 <tibble [3 x 1]>

src_tbl <- src_tbl %>% 
  mutate(src = as.factor(Sample_name),
         score_src = as.numeric(score))  %>% 
  select(src, score_src) %>% 
  tidyr::nest(score_src)

src_tbl  
# A tibble: 2 x 2
     src                    data
  <fctr>                  <list>
1     S1 <tibble [3 x 1]>
2     S2 <tibble [3 x 1]>

然后我创建一个包含所有样本名称组合的网格:

all_comb <- as_data_frame(expand.grid(src = src_tbl$src, ref = ref_tbl$ref))

all_comb
# A tibble: 6 x 2
     src    ref
  <fctr> <fctr>
1     S1     P1
2     S2     P1
3     S1     P2
4     S2     P2
5     S1     P3
6     S2     P3

现在，我们可以加入嵌套数据，并且我绑定(bind)了列，因此对于每个组合，必须有一个带有分数的列表列。

all_comb <- all_comb %>% 
  left_join(ref_tbl, by = "ref") %>% 
  left_join(src_tbl, by = "src") %>%
  mutate(data = purrr::map2(data.x, data.y, bind_cols)) %>%
  select(-data.x, -data.y)

all_comb 
# A tibble: 6 x 3
     src    ref                    data
  <fctr> <fctr>                  <list>
1     S1     P1 <tibble [3 x 2]>
2     S2     P1 <tibble [3 x 2]>
3     S1     P2 <tibble [3 x 2]>
4     S2     P2 <tibble [3 x 2]>
5     S1     P3 <tibble [3 x 2]>
6     S2     P3 <tibble [3 x 2]>

最后我图ks.test如果每个数据集，使用 broom 按要求获取 p.value。

final <- all_comb %>%
  mutate(ks = purrr::map(data,  ~ks.test(.$score_ref, .$score_src)),
  tidied = purrr::map(ks, broom::tidy)) %>%
  tidyr::unnest(tidied) %>%
  select(src, ref, p.value)
Warning message: cannot compute exact p-value with ties
Warning message: cannot compute exact p-value with ties

final
# A tibble: 6 x 3
     src    ref   p.value
  <fctr> <fctr>     <dbl>
1     S1     P1 0.5175508
2     S2     P1 0.5175508
3     S1     P2 0.6000000
4     S2     P2 0.6000000
5     S1     P3 0.6000000
6     S2     P3 0.6000000