Changing class from character to integer but retaining all the datas inside-CodePudding

q7 <- dbGetQuery(conn, "SELECT TailNum AS TailNum, AVG(ontime.DepDelay) AS avg_delay, ontime.Year AS Year, planes.Year AS yearmade FROM planes JOIN ontime USING(tailnum) WHERE ontime.Cancelled = 0 AND planes.Year != '' AND planes.Year != 'None' AND ontime.Diverted = 0 AND ontime.DepDelay > 0 GROUP BY TailNum ORDER BY avg_delay")

Codes that i have tried: q7 <- data.frame( yearmade = q7.yearmade, stringsAsFactors = FALSE)

^ Dataframe

Hi! Basically I would like to create a new column where the Year would subtract the yearmade and be placed into a new column, but before I could do that, I found out that the data I draw from another table into this dataframe shows as character(yearmade), is there any way to change it but retain the original data inside?

CodePudding user response：

First use as.numeric() to change yearmade into a numeric variable. Then you can simply compute the difference between Year and yearmade.

I believe this will work for you.

set.seed(1)

Year <- 2000:2022
yearmade <- sample(c('2000', '1999', '1998'), length(Year), replace = TRUE)
TailNum <- sample(c('N3738B', 'N3737C', 'N37342'), length(Year), replace = TRUE)
avg_delay <- 1:length(Year)
q7 <- data.frame(TailNum, avg_delay, Year, yearmade)

# compute difference and add to data frame
q7$year_diff <- q7$Year - as.numeric(q7$yearmade)

This retains the original data, but introduces a new column year_diff.

> str(q7)
'data.frame':   23 obs. of  5 variables:
 $ TailNum  : chr  "N3738B" "N3738B" "N3737C" "N3738B" ...
 $ avg_delay: int  1 2 3 4 5 6 7 8 9 10 ...
 $ Year     : int  2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 ...
 $ yearmade : chr  "2000" "1998" "2000" "1999" ...
 $ year_diff: num  0 3 2 4 4 7 8 8 9 11 ...