要将data.tableR中对象列中的第一个字母转换为大写，我们可以按照以下步骤操作 -
首先，创建一个data.table带有字符串列的对象。
然后，使用 sub 函数将字符串列中的第一个字母转换为大写。
让我们创建一个data.table如下所示的 -
library(data.table)
Countries<-
sample(c("india","china","russia","croatia","uk","usa","sudan","nepal","korea","germany","iceland"),25,replace=TRUE)
DT<-data.table(Countries)
DT输出结果执行时，上述脚本生成以下内容output(this output will vary on your system due to randomization)-
Countries 1: nepal 2: india 3: india 4: nepal 5: india 6: korea 7: germany 8: germany 9: sudan 10: iceland 11: india 12: india 13: nepal 14: korea 15: korea 16: nepal 17: croatia 18: nepal 19: usa 20: croatia 21: usa 22: india 23: nepal 24: germany 25: russia Countries
将第一个字母转换为大写
使用子函数将国家列中的第一个字母转换为大写 -
library(data.table)
Countries<-
sample(c("india","china","russia","croatia","uk","usa","sudan","nepal","korea","germany","iceland"),25,replace=TRUE)
DT<-data.table(Countries)
DT$Countries_new<-sub("(.)", "\\U\\1",DT$Countries,perl=TRUE)
DT输出结果Countries Countries_new 1: nepal Nepal 2: india India 3: india India 4: nepal Nepal 5: india India 6: korea Korea 7: germany Germany 8: germany Germany 9: sudan Sudan 10: iceland Iceland 11: india India 12: india India 13: nepal Nepal 14: korea Korea 15: korea Korea 16: nepal Nepal 17: croatia Croatia 18: nepal Nepal 19: usa Usa 20: croatia Croatia 21: usa Usa 22: india India 23: nepal Nepal 24: germany Germany 25: russia Russia Countries Countries_new