數(shù)據(jù)整理

1 tidyverse系統(tǒng)

https://www.math.pku.edu.cn/teachers/lidf/docs/Rbook/html/_Rbook/summary-manip.html#summm-tidyv
(完整版）
載入tidyverse包卿操，則magrittr包枚驻，readr包，dplyr包和tidyr包都會被自動載入:

library(tidyverse)

下面的例子中用如下的一個(gè)班的學(xué)生數(shù)據(jù)作為例子甫何，保存在如下class.csv文件中：

name,sex,age,height,weight
Alice,F,13,56.5,84
Becka,F,13,65.3,98
Gail,F,14,64.3,90
Karen,F,12,56.3,77
Kathy,F,12,59.8,84.5
Mary,F,15,66.5,112
Sandy,F,11,51.3,50.5
Sharon,F,15,62.5,112.5
Tammy,F,14,62.8,102.5
Alfred,M,14,69,112.5
Duke,M,14,63.5,102.5
Guido,M,15,67,133
James,M,12,57.3,83
Jeffrey,M,13,62.5,84
John,M,12,59,99.5
Philip,M,16,72,150
Robert,M,12,64.8,128
Thomas,M,11,57.5,85
William,M,15,66.5,112

讀入為tibble:

d.class <- read_csv(
  "class.csv", 
  col_types=cols(
  .default = col_double(),
  name=col_character(),
  sex=col_factor(levels=c("M", "F"))
))

這個(gè)數(shù)據(jù)框有19個(gè)觀測唁影，有如下5個(gè)變量：

name
sex
age
height
weight

R的NHANES擴(kuò)展包提供了一個(gè)規(guī)模更大的示例數(shù)據(jù)框NHANES耕陷，可以看作是美國扣除住院病人以外的人群的一個(gè)隨機(jī)樣本，有10000個(gè)觀測据沈，有76個(gè)變量哟沫，主題是個(gè)人的健康與營養(yǎng)方面的信息。僅作為教學(xué)使用而不足以作為嚴(yán)謹(jǐn)?shù)目蒲杏脭?shù)據(jù)锌介。原始數(shù)據(jù)的情況詳見http://www.cdc.gov/nchs/nhanes.htm嗜诀。載入NHANES數(shù)據(jù)框：

library(NHANES)
data(NHANES)

print(dim(NHANES))

## [1] 10000    76

print(names(NHANES))

##  [1] "ID"               "SurveyYr"         "Gender"           "Age"             
##  [5] "AgeDecade"        "AgeMonths"        "Race1"            "Race3"           
##  [9] "Education"        "MaritalStatus"    "HHIncome"         "HHIncomeMid"     
## [13] "Poverty"          "HomeRooms"        "HomeOwn"          "Work"            
## [17] "Weight"           "Length"           "HeadCirc"         "Height"          
## [21] "BMI"              "BMICatUnder20yrs" "BMI_WHO"          "Pulse"           
## [25] "BPSysAve"         "BPDiaAve"         "BPSys1"           "BPDia1"          
## [29] "BPSys2"           "BPDia2"           "BPSys3"           "BPDia3"          
## [33] "Testosterone"     "DirectChol"       "TotChol"          "UrineVol1"       
## [37] "UrineFlow1"       "UrineVol2"        "UrineFlow2"       "Diabetes"        
## [41] "DiabetesAge"      "HealthGen"        "DaysPhysHlthBad"  "DaysMentHlthBad" 
## [45] "LittleInterest"   "Depressed"        "nPregnancies"     "nBabies"         
## [49] "Age1stBaby"       "SleepHrsNight"    "SleepTrouble"     "PhysActive"      
## [53] "PhysActiveDays"   "TVHrsDay"         "CompHrsDay"       "TVHrsDayChild"   
## [57] "CompHrsDayChild"  "Alcohol12PlusYr"  "AlcoholDay"       "AlcoholYear"     
## [61] "SmokeNow"         "Smoke100"         "Smoke100n"        "SmokeAge"        
## [65] "Marijuana"        "AgeFirstMarij"    "RegularMarij"     "AgeRegMarij"     
## [69] "HardDrugs"        "SexEver"          "SexAge"           "SexNumPartnLife" 
## [73] "SexNumPartYear"   "SameSex"          "SexOrientation"   "PregnantNow"

變量ID是受試者編號， SurveyYr是調(diào)查年份掏湾，同一受試者可能在多個(gè)調(diào)查年份中有數(shù)據(jù)裹虫。變量中包括性別、年齡融击、種族筑公、收入等人口學(xué)數(shù)據(jù)，包括體重尊浪、身高匣屡、脈搏封救、血壓等基本體檢數(shù)據(jù)，以及是否糖尿病捣作、是否抑郁誉结、是否懷孕、已生產(chǎn)子女?dāng)?shù)等更詳細(xì)的健康數(shù)據(jù)券躁，運(yùn)動習(xí)慣惩坑、飲酒、性生活等行為方面的數(shù)據(jù)也拜。這個(gè)教學(xué)用數(shù)據(jù)集最初的使用者是Cashmere高中的Michelle Dalrymple 和新西蘭奧克蘭大學(xué)的Chris Wild以舒。

2 用filter()選擇行子集

行子集可以用行下標(biāo)選取，如d.class[8:12,]慢哈。函數(shù)head()取出數(shù)據(jù)框的前面若干行蔓钟， tail()取出數(shù)據(jù)框的最后若干行。
從d.class中選出年齡在13歲和13歲以下的女生：

d.class %>%
  filter(sex=="F", age<=13) %>%
  knitr::kable()

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