我有几个具有不同名称和相同日期变量的数据框。我想将变量的类型更改为yearmon
。我试图创建包含所有数据框的列表并更改类型,但是我无法unlist
保持原样。尝试了该站点中的所有代码,但始终会出现一些错误。我认为就我而言,我必须使用循环来解决这个问题。
这是到目前为止的代码:
df=data.frame(date=c("201101","201102","201103"),value=c(3,4,6))
df2=data.frame(date=c("201101","201102","201103"),value=c(3,4,6))
df3=data.frame(date=c("201101","201102","201103"),value=c(3,4,6))
library(zoo)
# list of all impoted dataframes
files <- ls()[sapply(mget(ls(), .GlobalEnv), is.data.frame)]
for (i in files){ #search for the dataframe name
for (j in length(get(i)[,1])){ #get the length of current data frame
d[j]=get(i)[j,1] #gets current data frame’s Date_col (the column with date)
d[j] <- as.yearmon(as.character(d[j,]), "%Y%m") #convert
assign(get(i)[j,1],d[j]) # an error shows here
}
}
这是我尝试用于列表中数据框的代码。
l.df <- lapply(ls(), function(x) if (class(get(x)) == "data.frame")
get(x))
files <- ls()[sapply(mget(ls(), .GlobalEnv), is.data.frame)]
names(l.df) <- files
lapply(l.df, transform, date=as.yearmon(as.character(date, "%Y%m")))
它返回日期的NA。
答案 0 :(得分:2)
我们可以做到(注意:在使用此解决方案时,您需要在形成数据集时将stringsAsFactors
设置为FALSE
或将日期转换为字符,请参见下文):
lapply(my_list ,
function(x)
transform(x,
date=zoo::as.yearmon(anytime::anydate(x$date))))
结果:
[[1]]
date value
1 Jan 2011 3
2 Feb 2011 4
3 Mar 2011 6
[[2]]
date value
1 Jan 2011 3
2 Feb 2011 4
3 Mar 2011 6
[[3]]
date value
1 Jan 2011 3
2 Feb 2011 4
3 Mar 2011 6
数据:
df=data.frame(date=c("201101","201102","201103"),value=c(3,4,6),
stringsAsFactors = F)
df2=data.frame(date=c("201101","201102","201103"),value=c(3,4,6),
stringsAsFactors = F)
df3=data.frame(date=c("201101","201102","201103"),value=c(3,4,6),
stringsAsFactors = F)