将带有“ NULL”的列转换为数字价值观 [英] Transform to numeric a column with "NULL" values
问题描述
我已经将数据集导入到R中，其中应该在其中包含数字的列中存在 NULL 。这使R将列类设置为字符或 factor ，这取决于您是否使用 stringAsFactors 参数。
I've imported a dataset into R where in a column which should be supposed to contain numeric values are present NULL. This make R set the column class to character or factor depending on if you are using or not the stringAsFactors argument.
这是数据集的结构。
> str(data)
'data.frame': 1016 obs. of 10 variables:
$ Date : Date, format: "2014-01-01" "2014-01-01" "2014-01-01" "2014-01-01" ...
$ Name : chr "Chi" "Chi" "Chi" "Chi" ...
$ Impressions: chr "229097" "3323" "70171" "1359" ...
$ Revenue : num 533.78 11.62 346.16 3.36 1282.28 ...
$ Clicks : num 472 13 369 1 963 161 1 7 317 21 ...
$ CTR : chr "0.21" "0.39" "0.53" "0.07" ...
$ PCC : chr "32" "2" "18" "0" ...
$ PCOV : chr "3470.52" "94.97" "2176.95" "0" ...
$ PCROI : chr "6.5" "8.17" "6.29" "NULL" ...
$ Dimension : Factor w/ 11 levels "100x72","1200x627",..: 1 3 4 5 7 8 9 10 11 1 ...
我想将PCROI列转换为数字，但包含 NULL s使其更难。
我试图解决将值 0 设置为当前值为 NULL ，但出现以下错误消息：
I would like to transform the PCROI column as numeric, but containing NULLs it makes this harder.
I've tried to get around the issue setting the value 0 to all observations where current value is NULL, but I got the following error message:
> data$PCROI[which(data$PCROI == "NULL"), ] <- 0
Error in data$PCROI[which(data$PCROI == "NULL"), ] <- 0 :
incorrect number of subscripts on matrix
下标的数目不正确我的想法是更改为 0 所有 NULL 观察值，然后使用 as.numeric 函数。
My idea was to change to 0 all the NULL observations and afterwards transform all the column to numeric using the as.numeric function.
推荐答案
您遇到语法错误：
data$PCROI[which(data$PCROI == "NULL"), ] <- 0 # will not work
data$PCROI[which(data$PCROI == "NULL")] <- 0 # will work
by the way you can say:
data$PCROI = as.numeric(data$PCROI)
它将自动将您的 NULL转换为NA。
it will convert your "NULL" to NA automatically.
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