Question

我有类似这样的数据。

   investor_name funding_round_type count
   <chr>         <chr>              <int>
 1 .406 Ventures angel                  1
 2 .406 Ventures other                  2
 3 .406 Ventures private-equity         1
 4 .406 Ventures series-a               5
 5 .406 Ventures series-b               2
 6 .406 Ventures series-c+              7
 7 .406 Ventures venture                1
 8 500 Startups  angel                 40

我想替换funding_round_type等于venture的所有实例，并用series-a，series-b或series-c+替换它。我想随机选择其中一个，前两个概率为40％，最后一个概率为20％。

my_df %>% 
   mutate(funding_round_type = ifelse(funding_round_type == "venture", 
                                      sample(c("series-a", "series-b", "series-c"), 1, replace = TRUE, prob = c(.4, .4, .2)),
                                      funding_round_type))

奇怪的是，sample()似乎只选择了一次，然后又恢复为每一行的选定值。我已经运行了几次，它仅用我的选项列表中的一个值替换了venture，并且不包含任何其他值的实例。

如何使sample（）在每一行上重新运行？

Answer 1

这是因为ifelse仅运行一次sample函数，并且您从中选择一个值，该值将为其他每个值循环使用。尝试做

library(dplyr)

my_df %>% 
  mutate(funding_round_type = ifelse(funding_round_type == "venture", 
        sample(c("series-a", "series-b", "series-c"), 
        sum(funding_round_type == "venture"),replace = TRUE, prob = c(.4, .4, .2)), 
        funding_round_type))

或与replace

my_df %>% 
   mutate(funding_round_type = replace(funding_round_type, 
   funding_round_type == "venture", sample(c("series-a", "series-b", "series-c"), 
   sum(funding_round_type == "venture"), replace = TRUE, prob = c(.4, .4, .2))))

您也可以直接替换它，而无需任何ifelse或任何包。

my_df$funding_round_type[my_df$funding_round_type == "venture"] <-  
    with(my_df, sample(c("series-a", "series-b", "series-c"), 
    sum(funding_round_type == "venture"), replace = TRUE, prob = c(.4, .4, .2)))

Answer 2

使用rowwise()将为每一行重新采样：

df %>%
  rowwise %>%
  mutate(funding_round_type = if_else(
    funding_round_type == "venture",
    sample(c("series-a", "series-b", "series-c+"), 1, prob = c(.4, .4, .2)),
    funding_round_type))

也是-次要的，但您不需要replace=TRUE，因为每次调用sample()仅提取一个样本。

Answer 3

我们可以使用data.table方法

library(data.table)
setDT(df)[funding_round_type == "venture", funding_round_type := 
    sample(c("series-a", "series-b", "series-c+"), 1, prob = c(.4, .4, .2))][]
#    investor_name funding_round_type count
#1: .406 Ventures              angel     1
#2: .406 Ventures              other     2
#3: .406 Ventures     private-equity     1
#4: .406 Ventures           series-a     5
#5: .406 Ventures           series-b     2
#6: .406 Ventures          series-c+     7
#7: .406 Ventures           series-b     1
#8:  500 Startups              angel    40

或使用case_when中的tidyverse

library(tidyerse)
df %>%
     mutate(funding_round_type = case_when(funding_round_type == "venture" ~ 
        sample(c("series-a", "series-b", "series-c+"), 1, prob = c(.4, .4, .2)),
       TRUE ~ funding_round_type))
#  investor_name funding_round_type count
#1 .406 Ventures              angel     1
#2 .406 Ventures              other     2
#3 .406 Ventures     private-equity     1
#4 .406 Ventures           series-a     5
#5 .406 Ventures           series-b     2
#6 .406 Ventures          series-c+     7
#7 .406 Ventures           series-a     1
#8  500 Startups              angel    40

数据

df <- structure(list(investor_name = c(".406 Ventures", ".406 Ventures", 
".406 Ventures", ".406 Ventures", ".406 Ventures", ".406 Ventures", 
".406 Ventures", "500 Startups"), funding_round_type = c("angel", 
"other", "private-equity", "series-a", "series-b", "series-c+", 
"venture", "angel"), count = c(1L, 2L, 1L, 5L, 2L, 7L, 1L, 40L
)), class = "data.frame", row.names = c("1", "2", "3", "4", "5", 
"6", "7", "8"))

如何在ifelse语句中更新我的sample（）？

3 个答案:

数据