正则表达式 – 在r中的ifelse模式匹配

发布时间：2020-12-14 06:06:44 所属栏目：百科来源：网络整理

导读：如果模式匹配,我想用两个值之一填充一个新列. 这是我的数据框： df - structure(list(loc_01 = c("apis","indu","isro","miss","non_apis","non_indu","non_isro","non_miss","non_piro","non_sacn","non_slbe","non_voya","piro","sacn","slbe","voya"),loc

如果模式匹配,我想用两个值之一填充一个新列.

这是我的数据框：

df <- structure(list(loc_01 = c("apis","indu","isro","miss","non_apis","non_indu","non_isro","non_miss","non_piro","non_sacn","non_slbe","non_voya","piro","sacn","slbe","voya"),loc01_land = c(165730500,62101800,540687600,161140500,1694590200,1459707300,1025051400,1419866100,2037064500,2204629200,1918840500,886299300,264726000,321003900,241292700,530532000)),class = "data.frame",row.names = c(NA,-16L),.Names = c("loc_01","loc01_land"))

看起来像这样……

loc_01 loc01_land
1      apis  165730500
2      indu   62101800
3      isro  540687600
4      miss  161140500
5  non_apis 1694590200
6  non_indu 1459707300
7  non_isro 1025051400
8  non_miss 1419866100
9  non_piro 2037064500
10 non_sacn 2204629200
11 non_slbe 1918840500
12 non_voya  886299300
13     piro  264726000
14     sacn  321003900
15     slbe  241292700
16     voya  530532000

我想在df中添加一个名为’loc_01’的列.如果loc_01包含non,则返回’outside’,如果它不包含non,则返回’inside’.这是我的ifelse语句,但我遗漏了一些东西,因为它只返回false值.

df$loc01 <- ifelse(df$loc_01=="non",'outside','inside')

由此产生的df ……

loc_01 loc01_land  loc01
1      apis  165730500 inside
2      indu   62101800 inside
3      isro  540687600 inside
4      miss  161140500 inside
5  non_apis 1694590200 inside
6  non_indu 1459707300 inside
7  non_isro 1025051400 inside
8  non_miss 1419866100 inside
9  non_piro 2037064500 inside
10 non_sacn 2204629200 inside
11 non_slbe 1918840500 inside
12 non_voya  886299300 inside
13     piro  264726000 inside
14     sacn  321003900 inside
15     slbe  241292700 inside
16     voya  530532000 inside

谢谢
-al

解决方法

要检查字符串是否包含某个子字符串,您不能使用==,因为它执行完全匹配(即,仅当字符串完全为“非”时才返回true).
您可以使用例如执行模式匹配的grepl函数(属于 grep family of functions)：

df$loc01 <- ifelse(grepl("non",df$loc_01),'inside')

结果：

> df
     loc_01 loc01_land   loc01
1      apis  165730500  inside
2      indu   62101800  inside
3      isro  540687600  inside
4      miss  161140500  inside
5  non_apis 1694590200 outside
6  non_indu 1459707300 outside
7  non_isro 1025051400 outside
8  non_miss 1419866100 outside
9  non_piro 2037064500 outside
10 non_sacn 2204629200 outside
11 non_slbe 1918840500 outside
12 non_voya  886299300 outside
13     piro  264726000  inside
14     sacn  321003900  inside
15     slbe  241292700  inside
16     voya  530532000  inside

（编辑：李大同）

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