[英]Does anybody know how to plot a graph in R with RGB values of a core sediment image?
[英]Does anybody know how to write an expression in R that counts NA values and valid values for a dataframe?
一个提示是您将使用table()
和is.na
对于此表达式,您尝试查找NA
计数/总计的一列中有特定值。
例:
team color state div
1 R NY 1
2 G WI 1
3 P ND 2
4 O CO 2
5 B TX 1
6 NA MI 2
7 Y CA 1
8 V NA 2
您能帮我写一个表达式,专门用div
( 1
和2
)计算NA
和有效值吗?
我们可以通过将'data.frame'转换为'data.table'( setDT(df1)
)来使用data.table
,并按'div'分组,我们不unlist
的子集( .SD
),转换为is.na
逻辑向量,并用sum
计数TRUE值以获得NA的计数,类似地取反( !
)和sum
以获得非NA元素的计数。
library(data.table)
setDT(df1)[, {v1 <- is.na(unlist(.SD));list(countNA = sum(v1),
countNoNA = sum(!v1)) } , by = div]
# div countNA countNoNA
#1: 1 0 12
#2: 2 2 10
或使用table
和is.na
,我们复制'div'列以使其长度与未unlist
列的长度相同,然后应用table
。
table(df1$div[row(df1[-4])], is.na(unlist(df1[-4])))
# FALSE TRUE
# 1 12 0
# 2 10 2
OP出于复制目的将帖子中的数据更改为图像
df1 <- structure(list(team = 1:8, color = c("R", "G", "P", "O", "B",
NA, "Y", "V"), state = c("NY", "WI", "ND", "CO", "TX", "MI",
"CA", NA), div = c(1L, 1L, 2L, 2L, 1L, 2L, 1L, 2L)), .Names = c("team",
"color", "state", "div"), class = "data.frame", row.names = c(NA, -8L))
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