当前位置:网站首页>decast id.var measure.var数据拆分与合并
decast id.var measure.var数据拆分与合并
2022-04-23 12:58:00 【qq_52813185】
R之data.table -melt/dcast(数据拆分和合并)
写在前面:数据整形的过程确实和揉面团有些类似,先将数据通过melt()函数将数据揉开,然后再通过dcast()函数将数据重塑成想要的形状
reshape2包:
melt-把宽格式数据转化成长格式。
cast-把长格式数据转化成宽格式。(dcast-输出时返回一个数据框。acast-输出时返回一个向量/矩阵/数组。)
注:melt是数据融合的意思,它做的工作其实就是把数据由“宽”转“长”。
cast 函数的作用除了还原数据外,还可以对数据进行整合。
dcast 输出数据框。公式的左边每个变量都会作为结果中的一列,而右边的变量被当成因子类型,每个水平都会在结果中产生一列。
tidyr包:
gather-把宽度较大的数据转换成一个更长的形式,它类比于从reshape2包中融合函数的功能
spread-把长的数据转换成一个更宽的形式,它类比于从reshape2包中铸造函数的功能。
data.table包:
data.table的函数melt 和dcast 是增强包reshape2里同名函数的扩展
library(data.table)
ID <- c(NA,1,2,2)
Time <- c(1,2,NA,1)
X1 <- c(5,3,NA,2)
X2 <- c(NA,5,1,4)
mydata <- data.table(ID,Time,X1,X2)
mydata
## ID Time X1 X2
## 1: NA 1 5 NA
## 2: 1 2 3 5
## 3: 2 NA NA 1
## 4: 2 1 2 4
md <- melt(mydata, id=c("ID","Time")) #or md <- melt(mydata, id=1:2)
#melt以使每一行都是一个唯一的标识符-变量组合
md #将第一列作为id列,其他列全部融合就可以了
## ID Time variable value
## 1: NA 1 X1 5
## 2: 1 2 X1 3
## 3: 2 NA X1 NA
## 4: 2 1 X1 2
## 5: NA 1 X2 NA
## 6: 1 2 X2 5
## 7: 2 NA X2 1
## 8: 2 1 X2 4
将变量"variable",和"value"揉合在一起,结果产生了新的两列,一列是变量variable,指代是哪个揉合变量,另外一列是取值value,即变量对应的值。我们也称这样逐行排列的方式称为长数据格式
melt:数据集的融合是将它重构为这样一种格式:每个测量变量独占一行,行中带有要唯一确定这个测量所需的标识符变量。
str(mydata)
## Classes 'data.table' and 'data.frame': 4 obs. of 4 variables:
## $ ID : num NA 1 2 2
## $ Time: num 1 2 NA 1
## $ X1 : num 5 3 NA 2
## $ X2 : num NA 5 1 4
## - attr(*, ".internal.selfref")=<externalptr>
str(md)
## Classes 'data.table' and 'data.frame': 8 obs. of 4 variables:
## $ ID : num NA 1 2 2 NA 1 2 2
## $ Time : num 1 2 NA 1 1 2 NA 1
## $ variable: Factor w/ 2 levels "X1","X2": 1 1 1 1 2 2 2 2
## $ value : num 5 3 NA 2 NA 5 1 4
## - attr(*, ".internal.selfref")=<externalptr>
setcolorder(md,c("ID","variable","Time","value")) ##setcolorder()可以用来修改列的顺序。
md
## ID variable Time value
## 1: NA X1 1 5
## 2: 1 X1 2 3
## 3: 2 X1 NA NA
## 4: 2 X1 1 2
## 5: NA X2 1 NA
## 6: 1 X2 2 5
## 7: 2 X2 NA 1
## 8: 2 X2 1 4
mdr <- melt(mydata, id=c("ID","Time"),variable.name="Xzl",value.name="Vzl",na.rm = TRUE) #variable.name定义变量名
mdr
## ID Time Xzl Vzl
## 1: NA 1 X1 5
## 2: 1 2 X1 3
## 3: 2 1 X1 2
## 4: 1 2 X2 5
## 5: 2 NA X2 1
## 6: 2 1 X2 4
mdr1 <- melt(mydata, id=c("ID","Time"),variable.name="Xzl",value.name="Vzl",measure.vars=c("X1"),na.rm = TRUE) #measure.vars筛选
mdr1
## ID Time Xzl Vzl
## 1: NA 1 X1 5
## 2: 1 2 X1 3
## 3: 2 1 X1 2
md[Time==1]
## ID variable Time value
## 1: NA X1 1 5
## 2: 2 X1 1 2
## 3: NA X2 1 NA
## 4: 2 X2 1 4
md[Time==2]
## ID variable Time value
## 1: 1 X1 2 3
## 2: 1 X2 2 5
#执行整合
# rowvar1 + rowvar2 + ... ~ colvar1 + colvar2 + ...
# 在这个公式中,rowvar1 + rowvar2 + ... 定义了要划掉的变量集合,以确定各行的内容,而colvar1 + colvar2 + ... 则定义了要划掉的、确定各列内容的变量集合。
newmd<- dcast(md, ID~variable, mean)
newmd
## ID X1 X2
## 1: 1 3 5.0
## 2: 2 NA 2.5
## 3: NA 5 NA
newmd2<- dcast(md, ID+variable~Time)
newmd2
## ID variable 1 2 NA
## 1: 1 X1 NA 3 NA
## 2: 1 X2 NA 5 NA
## 3: 2 X1 2 NA NA
## 4: 2 X2 4 NA 1
## 5: NA X1 5 NA NA
## 6: NA X2 NA NA NA
#ID+variable~Time 使用Time对(ID,variable)分组 Time:1,2,NA 类似excel的数据透析
newmd3<- dcast(md, ID~variable+Time)
newmd3 #variable:X1,X2 Time:1,2,NA 类似excel的数据透析
## ID X1_1 X1_2 X1_NA X2_1 X2_2 X2_NA
## 1: 1 NA 3 NA NA 5 NA
## 2: 2 2 NA NA 4 NA 1
## 3: NA 5 NA NA NA NA NA
即使只是凡世中一颗小小的尘埃,命运也要由自己主宰,像向日葵般,迎向阳光、勇敢盛开
版权声明
本文为[qq_52813185]所创,转载请带上原文链接,感谢
https://blog.csdn.net/qq_52813185/article/details/124359601
边栏推荐
- Luogu p5540 [balkanoi2011] timeismoney | minimum product spanning tree problem solution
- 将新增和编辑的数据同步更新到列表
- PC starts multiple wechat at one time
- Object.keys后key值数组乱序的问题
- Go language array operation
- (1) Openjuterpyrab comparison scheme
- 22. Bracket generation
- Object. The disorder of key value array after keys
- Read the data in Presto through sparksql and save it to Clickhouse
- Customize classloader and implement hot deployment - use loadclass
猜你喜欢
22. Bracket generation
Process virtual address space partition
梳理网络IP代理的几大用途
Importerror after tensorflow installation: DLL load failed: the specified module cannot be found, and the domestic installation is slow
Aviation core technology sharing | overview of safety characteristics of acm32 MCU
风尚云网学习-h5的input:type属性的image属性
Remote access to raspberry pie at home (Part 1)
风尚云网学习-input属性总结
SSL certificate refund instructions
Fashion cloud learning - input attribute summary
随机推荐
Unable to create servlet under SRC subfile of idea
22. 括号生成
Golang realizes regular matching: the password contains at least one digit, letter and special character, and the length is 8-16
SSM framework series - annotation development day2-2
JDBC connection pool
The continuous construction of the Internet industry platform is not only able to collect traffic
leetcode-791. 自定义字符串排序
Luogu p3236 [hnoi2014] picture frame solution
Subscribe to Alibaba demo send business messages
Connect orcale
SSL certificate refund instructions
Unlock openharmony technology day! The annual event is about to open!
精度、速度完美平衡,最新图像分割SOTA模型重磅发布!!!
If you were a golang interviewer, what questions would you ask?
Pytorch: a pit about the implementation of gradreverselayer
21 days learning mongodb notes
产品开发都应该知道的8个网站,增强工作体验
Buuctf Web [gxyctf2019] no dolls
Resolve disagrees about version of symbol device_ create
Custom nail robot alarm