如何按R中的行中的值选择列

I have a large data frame marking occurrences of trigrams in a string, where the strings are the rows, the trigrams are the columns, and the values mark whether an trigram occurs in a string.

我有一个大的数据框,标记字符串中出现三元组,其中字符串是行,三元组是列,值表示三角形是否出现在字符串中。

so something like this:

所以这样的事情:

strs <- c('this', 'that', 'chat', 'chin')
thi <- c(1, 0, 0, 0)
tha <- c(0, 1, 0, 0)
hin <- c(0, 0, 0, 1)
hat <- c(0, 1, 1, 0)
df <- data.frame(strs, thi, tha, hin, hat)
df

#  strs thi tha hin hat
#1 this   1   0   0   0
#2 that   0   1   0   1
#3 chat   0   0   0   1
#4 chin   0   0   1   0

I want to get all of the columns/trigrams that have a 1 for a given row or a given string.

我想获得给定行或给定字符串的所有列/三元组。

So for row 2, the string 'that', the result would a data frame that looks like this:

因此对于第2行,字符串'that',结果将是一个如下所示的数据框:

  str tha hat
1 this  0   0
2 that  1   1
3 chat  0   1
4 chin  0   0

How could I do this?

我怎么能这样做?

2 个解决方案

#1

This will give you the desired output df.

这将为您提供所需的输出df。

givenStr <- "that"
row <- df[df$strs==givenStr,]
df[,c(1,1+which(row[,-1]==1))]

#2

In a one liner:

在一个班轮:

df[as.logical(df[df$strs=='that',])]

#  strs tha hat
#1 this   0   0
#2 that   1   1
#3 chat   0   1
#4 chin   0   0

#1