[英]How to replace certain values in a specific rows and columns with NA in R?
In my data frame, I want to replace certain blank cells and cells with values with NA. 在我的数据框中,我想用NA替换某些空白单元格和具有值的单元格。 But the cells I want to replace with NAs has nothing to do with the value that cell stores, but with the combination of row and column it is stored in.
但是我要替换为NA的单元格与单元格存储的值无关,但是与行和列的组合存储在其中。
Here's a sample data frame DF: 这是一个示例数据帧DF:
Fruits Price Weight Number of pieces
Apples 20 2 10
Oranges 15 4 16
Pineapple 40 8 6
Avocado 60 5 20
I want to replace Pineapple'e weight to NA and Orange's number of pieces to NA. 我想将Pineapple'e的重量替换为NA,将Orange的件数替换为NA。
DF$Weight[3] <- NA
DF$`Number of pieces`[2] <- NA
This replaces any value that's stored in that position and that may change. 这将替换存储在该位置的任何值,并且可能会更改。 I want to use specific row and column names to do this replacement so the position of value becomes irrelevant.
我想使用特定的行和列名称进行替换,因此值的位置变得无关紧要。
Output: 输出:
Fruits Price Weight Number of pieces
Apples 20 2 10
Oranges 15 4 NA
Pineapple 40 NA 6
Avocado 60 5 20
But if order of the table is changed, this would replace wrong values with NA. 但是,如果更改表的顺序,则会用NA替换错误的值。
How should I do this? 我应该怎么做?
Here is a way using function is.na<-
. 这是使用函数
is.na<-
。
is.na(DF$Weight) <- DF$Fruits == "Pineapple"
is.na(DF$`Number of pieces`) <- DF$Fruits == "Oranges"
DF
# Fruits Price Weight Number of pieces
#1 Apples 20 2 10
#2 Oranges 15 4 NA
#3 Pineapple 40 NA 6
#4 Avocado 60 5 20
Data in dput
format. dput
格式的数据。
DF <-
structure(list(Fruits = structure(c(1L, 3L, 4L, 2L),
.Label = c("Apples", "Avocado", "Oranges", "Pineapple"),
class = "factor"), Price = c(20L, 15L, 40L, 60L),
Weight = c(2L, 4L, 8L, 5L), `Number of pieces` = c(10L,
16L, 6L, 20L)), class = "data.frame", row.names = c(NA, -4L))
Since you data structure is 2 dimensional you can find the indices of the rows containing a specific value first and use this information. 由于您的数据结构是二维的,因此可以先找到包含特定值的行的索引,然后使用此信息。
which(DF$Fruits == "Pineapple")
[1] 3
DF$Weight[which(DF$Fruits == "Pineapple")] <- NA
You should be aware of that which
will return a vector, so if you have multiple fruits called "Pineapple" then the previous command will return all indices of them. 你应该知道的是
which
会返回一个矢量,所以如果你有多个水果被称为“菠萝”,那么前面的命令将返回他们的各项指标。
library(dplyr)
df %>%
mutate(Weight=ifelse(Fruits=="Pineapple",NA,Weight),
Number=ifelse(Fruits=="Oranges",NA,Number))#use Number of Pieces
Result: Number of pieces was truncated to Number due to reading data. 结果:由于读取数据,件数被截断为Number。
Fruits Price Weight Number
1 Apples 20 2 10
2 Oranges 15 4 NA
3 Pineapple 40 NA 6
4 Avocado 60 5 20
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