使用 R 重复替换单词答案

【问题标题】：Using R to repeatedly replace words使用 R 重复替换单词
【发布时间】：2015-08-19 16:40:19
【问题描述】：

我有一句话，分两行打印出来：

cat("Today is Monday and it is sunny.\nMonday is a sunny day\n")

我有两个列表：

day<-c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
weather<-c("sunny", "cloudy", "rainy", "stormy","sunny", "cloudy", "rainy")

我正在尝试生成一个文本文件，该文件将包含上面的字符串变量，但列表中包含每天和天气变量。

所以我会：

Today is Monday and it is sunny.
Monday is a sunny day
Today is Tuesday and it is cloudy.
Tuesday is a cloudy day
Today is Wednesday and it is rainy.
Wednesdady is a rainy day

....等等。

我想知道这在 R 中是否可行。我是一个相对较新的 R 初学者，所以任何解释都将不胜感激！

【问题讨论】：

标签： r loops replace

【解决方案1】：

day<-c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
weather<-c("sunny", "cloudy", "rainy", "stormy","sunny", "cloudy", "rainy")

sprintf 可用于将字符串插入到其他字符串中：

txt1 <- sprintf("Today is %s and it is %s.",day,weather)
txt2 <- sprintf("%s is a %s day",day,weather)

现在交错结果（将它们作为矩阵的行组合在一起，然后按列提取元素 - 还有其他方法可以做到这一点，但这是一种有用的快速而简单的方法）：

c(rbind(txt1,txt2))

您可以使用 cat() 和 sep="\n" 或 paste() 和 collapse="\n" 将结果向量放入单个换行符分隔的结果中......或者只使用 writeLines() 将结果向量发送到文本文件。

【讨论】：

【解决方案2】：

您可以使用cat 构建一个简单的循环并打印。

for (i in 1:length(day)) {
    cat("Today is", day[i], "and it is a", weather[i], "day.\n")
    cat(day[i], "is a", weather[i], "day\n")
}

# Today is Monday and it is a sunny day.
# Monday is a sunny day
# Today is Tuesday and it is a cloudy day.
# Tuesday is a cloudy day
# Today is Wednesday and it is a rainy day.
# Wednesday is a rainy day
# Today is Thursday and it is a stormy day.
# Thursday is a stormy day
# Today is Friday and it is a sunny day.
# Friday is a sunny day
# Today is Saturday and it is a cloudy day.
# Saturday is a cloudy day
# Today is Sunday and it is a rainy day.
# Sunday is a rainy day

这会遍历矢量的所有元素，并根据索引访问每天和天气。

Day: "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" "Sunday"
Index:  1         2          3           4         5         6        7

在循环的第一次迭代中，i 设置为 1，day[i] 设置为 "Monday"。同样，weather[i] 是"sunny"，因为"sunny" 是weather 向量中的第一个元素。该模式在整个向量上重复。

所以在第一次迭代时，第一句话是

cat("Today is", "Monday", "and it is a", "sunny", "day.\n")

默认情况下，cat 用空格分隔连续值。所以这会打印出我们正在寻找的句子。第二句也是如此。

【讨论】：