如果否-在R中带有子字符串的句子

如何解决如果否-在R中带有子字符串的句子

我有一个df，我想为screen_name列中所有列的首字母加上子串，但名称为'frank'的单元格除外。我的所有尝试都被R忽略（子字符串在所有单元格上执行）。为什么？

df <- data.frame("screen_name" = c("august","berit","christopher","david","erica","frank"),"rt_name" = c("berit","august","frank","christopher"))

#IF-sentence with '%!like%' 
'%!like%' <- function(x,y)!('%like%'(x,y))
df$screen_name<- if(df$screen_name %!like% ('frank')) {substr(df$screen_name,1,2)}

#IF-sentence with !=
df$screen_name<- if(df$screen_name != 'frank') {substr(df$screen_name,2)}

我正在寻找包含％！like％或相似名称的解决方案，因为df中的名称可能会有所不同，而且我并不总是完全匹配。

我的预期输出是

df_exp <- data.frame("screen_name" = c("au","be","ch","da","er","christopher"))

谢谢！

解决方法

您可以尝试结合使用ifelse和grepl来检查输入屏幕名称是否恰好是frank：

df$screen_name <- ifelse(!grepl("^frank$",df$screen_name),substr(df$screen_name,1,2),df$screen_name)
df

  screen_name     rt_name
1          au       berit
2          be      august
3          ch       david
4          da       erica
5          er       frank
6       frank christopher

数据：

df <- data.frame(screen_name = c("august","berit","christopher","david","erica","frank"),rt_name = c("berit","august","frank","christopher"),stringsAsFactors=FALSE)