我有一个包含数千行和列的数据框,在这里我需要计算从第一行到其他每行(row1–row2,row1–row3,row1–row4,…)的字符变量的变化,并输出总计更改数量进入新列。
df <- data_frame(
a = c("1 2", "1 2", "2 2", "2 2"),
b = c("2 1", "1 2", "1 2","1 2"),
c = c("1 1", "1 2", "2 1","2 2"),
d = c("1 1", "1 1", "2 1","2 1")
)
df
a b c d
<chr> <chr> <chr> <chr>
1 1 2 2 1 1 1 1 1
2 1 2 1 2 1 2 1 1
3 2 2 1 2 2 1 2 1
4 2 2 1 2 2 2 2 1
我想计算从第1行到第2行,从第1行到第3行的每个元素之间的字符不匹配,依此类推。这样我就知道了:
a b c d e
1 1 2 2 1 1 1 1 1 NA #No mismatches to count since this is the first row.
2 1 2 1 2 1 2 1 1 3
3 2 2 1 2 2 1 2 1 5
4 2 2 1 2 2 2 2 1 6
关于如何实现这一目标的任何想法?
dplyr
和purrr
一种方法可能是:
bind_cols(df, df %>%
mutate_all(~ strsplit(., " ", fixed = TRUE)) %>%
mutate_all(~ map2_int(.x = ., .y = .[1], ~ sum(.x != .y))) %>%
transmute(e = rowSums(select(., everything()))))
a b c d e
<chr> <chr> <chr> <chr> <dbl>
1 1 2 2 1 1 1 1 1 0
2 1 2 1 2 1 2 1 1 3
3 2 2 1 2 2 1 2 1 5
4 2 2 1 2 2 2 2 1 6
您也可以这样做:
library(dplyr)
library(purrr)
df %>%
mutate(e = pmap(., ~toString(c(...)) %>% charToRaw),
e = map_dbl(e, ~ sum(.x != e[[1]])))
# A tibble: 4 x 5
a b c d e
<chr> <chr> <chr> <chr> <dbl>
1 1 2 2 1 1 1 1 1 0
2 1 2 1 2 1 2 1 1 3
3 2 2 1 2 2 1 2 1 5
4 2 2 1 2 2 2 2 1 6