[英]r - copy value based on match in another column
In this data frame: 在此数据框中:
Item <- c("A","B","A","A","A","A","A","B")
Trial <- c("Fam","Fam","Test","Test","Test","Test","Test","Test")
Condition <-c("apple","cherry","Trash","Trash","Trash","Trash","Trash","Trash")
ID <- c(rep("01",8))
df <- data.frame(cbind(Item,Trial,Condition,ID))
I would like to replace the "Trash" value of df$condition
at df$Trial == "Test"
. 我想在df$Trial == "Test"
替换df$condition
的“Trash”值。 The new value of df$condition
should be a copy df$condition
at df$Trial == "Fam"
, based on a match of Fam and Test Trials in df$Item
. 根据df$Item
中Fam和Test Trials的匹配, df$condition
的新值应该是df$Trial == "Fam"
的副本df$condition
。
So my final data frame should look like this 所以我的最终数据框应该是这样的
Item Trial Condition ID
1 A Fam apple 01
2 B Fam cherry 01
3 A Test apple 01
4 A Test apple 01
5 A Test apple 01
6 A Test apple 01
7 A Test apple 01
8 B Test cherry 01
Ultimately I would like to do this for unique ID's in my original data frame. 最后,我想在原始数据框中为唯一ID执行此操作。 So I guess I will have to apply the function within ddply
or so later on. 所以我想我将不得不在ddply
应用该函数。
You could do a self binary join on df
when Trial != "Test"
and update the Condition
column by reference using the data.table
package, for instance 您可以在Trial != "Test"
时在df
上执行自我二进制连接 ,并使用data.table
包通过引用更新Condition
列,例如
library(data.table) ## V 1.9.6+
setDT(df)[df[Trial != "Test"], Condition := i.Condition, on = c("Item", "ID")]
df
# Item Trial Condition ID
# 1: A Fam apple 01
# 2: B Fam cherry 01
# 3: A Test apple 01
# 4: A Test apple 01
# 5: A Test apple 01
# 6: A Test apple 01
# 7: A Test apple 01
# 8: B Test cherry 01
Or (with some modification of @docendos) suggestion, simply 或者(对@docendos进行一些修改)建议,简单地说
setDT(df)[, Condition := Condition[Trial != "Test"], by = .(Item, ID)]
Here is an option using dplyr
这是使用dplyr
的选项
library(dplyr)
distinct(df) %>%
filter(Trial=='Fam') %>%
left_join(df, ., by = c('Item', 'ID')) %>%
mutate(Condition = ifelse(Condition.x=='Trash',
as.character(Condition.y), as.character(Condition.x))) %>%
select(c(1,2,4,7))
Or as suggested by @docendodiscimus 或者按照@docendodiscimus的建议
df %>%
group_by(ID, Item) %>%
mutate(Condition = Condition[Condition != "Trash"])
You could also just create a for-loop and loop through all the values that need to be changed. 您还可以创建一个for循环并循环遍历所有需要更改的值。 This setup makes it easy to add other items and/or change the type of condition later on. 此设置可以轻松添加其他项目和/或稍后更改条件类型。
> for(i in 1:nrow(df)) {
>
> if(df[i, 1] == "A") {
> df2[i, 3] <- "apple"
> }
> else if(df[i, 1] == "B") {
> df2[i, 3] <- "cherry"
> }
> }
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