r：有条件地替换列子集中的值 [英] r: conditionally replace values in a subset of columns

问题描述

我有一个这样的数据框：

I have a dataframe like so:

sport   contract start contract end visits spends purchases
basket   2013-10-01     2014-10-01   12      14      23
basket   2014-02-12     2015-03-03   23      11      7
football 2015-02-12     2016-03-03   23      11      7
basket   2016-07-17     2013-09-09   12       7      13

我想有条件地更换基于变量体育和合同开始的[4：6]列包含NA。
例如：

I would like to conditionally replace the columns [4:6] with NAs, based on the variables "sport" and "contract start". So for instance:

i1 <- which(df$sport =="basket" & df$contract_start>="2014-01-01")

将对我的条件所在的所有行进行索引遇见。
是否有一段简单的代码可以添加到上述代码中，在上述条件下，它将用NA替换df [4：6]？
我想结束这样的事情：

will index all the rows in which my conditions are met. Is there an easy piece of code to add to the above, that will replace df[4:6] with NAs given the above conditions? I would like to end up with something like that:

sport   contract start contract end visits spends purchases
basket   2013-10-01     2014-10-01   12      14      23
basket   2014-02-12     2015-03-03   NA      NA      NA
football 2015-02-12     2016-03-03   23      11      7
basket   2016-07-17     2013-09-09   NA      NA      NA

谢谢！
A。

Thanks! A.

推荐答案

您只需指定要用NA替换的行和列，然后进行分配 NA ：

You can simply specify the rows and columns that you would like to replace with NA, and assign NA to it:

df[df$sport =="basket" & df$contract_start>="2014-01-01", 4:6] <- NA

df
#      sport contract_start contract_end visits spends purchases
# 1   basket     2013-10-01   2014-10-01     12     14        23
# 2   basket     2014-02-12   2015-03-03     NA     NA        NA
# 3 football     2015-02-12   2016-03-03     23     11         7
# 4   basket     2016-07-17   2013-09-09     NA     NA        NA

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