如何从R中的数据框架中选择特定日期的某些行 [英] How to select some rows with specific date from a data frame in R

问题描述

我有一个大的数据集，我想特别挑选一些行，我想知道有人可以帮助我吗？非常感谢你的帮助!!

例如，如果我只想从2/1 / 2008-5 / 1/2008加上9 / 1 / 2008-11 / 1/2008，我该怎么办？
非常感谢！

任何人都可以帮忙？

  date mpressure mxtemp 
 2008-01-01 1025.3 15.7 
 2008-01-02 1025.6 16.0< 
 2008-01-03 1023.6 18.1< 
 2008-01-04 1021.8 18.4< 
 2008-01-05 1020.1 20.9< 
 2008-01-06 1019.7 20.7 
 2008-01-07 1018.4 24.0 
 2008-01-08 1016.7 23.7 
 2008-01-09 1015.3 24.5< 
 2008-01-10 1014.3 21.8< 
 2008-01-11 1012.9 23.4< 
  

然后我会得到这样的东西？

  date mpressure mxtemp 
 2008-01-02 1025.6 16.0< 
 2008-01-03 1023.6 18.1< 
 2008-01-04 1021.8 18.4< 
 2008-01-05 1020.1 20.9< 
 2008-01-09 1015.3 24.5< 
 2008-01-10 1014.3 21.8< 
 2008-01-11 1012.9 23.4< 
  

解决方案

将日期列转换为日期 -type：

  df $ date<  -  as.Date（df $ date）
  

然后根据您的规格进行子集：

<$ p （df，df [（date> =2008-01-02&=2008-01-05））
（date> =2008-01-09& date< =2008-01-11））]
＃date mpressure mxtemp
＃2 2008-01-02 1025.6 16.0
＃3 2008-01-03 1023.6 18.1
＃4 2008-01-04 1021.8 18.4
＃5 2008-01-05 1020.1 20.9
＃9 2008-01-09 1015.3 24.5
＃10 2008-01-10 1014.3 21.8
＃11 2008-01-11 1012.9 23.4

I have a large dataset and I want to pick out some of the rows particularly, I am wondering if anyone could help me with this? Thank you so much for your help!!

For example, if I just want pick out rows that are from 2/1/2008-5/1/2008 plus 9/1/2008-11/1/2008, how can I do that? Thank you very much!!

Can anyone please help?

date    mpressure   mxtemp
2008-01-01  1025.3  15.7
2008-01-02  1025.6  16.0    <   
2008-01-03  1023.6  18.1    <
2008-01-04  1021.8  18.4    <
2008-01-05  1020.1  20.9    <
2008-01-06  1019.7  20.7
2008-01-07  1018.4  24.0
2008-01-08  1016.7  23.7
2008-01-09  1015.3  24.5    <
2008-01-10  1014.3  21.8    <
2008-01-11  1012.9  23.4    <

And then I will get something like this?

date    mpressure   mxtemp
2008-01-02  1025.6  16.0    <   
2008-01-03  1023.6  18.1    <
2008-01-04  1021.8  18.4    <
2008-01-05  1020.1  20.9    <
2008-01-09  1015.3  24.5    <
2008-01-10  1014.3  21.8    <
2008-01-11  1012.9  23.4    <

解决方案

Convert your date column to Date-type:

df$date <- as.Date(df$date)

Then subset according to your specifications:

with(df, df[(date >= "2008-01-02" & date <= "2008-01-05") | 
                                 (date >= "2008-01-09" & date <= "2008-01-11"), ])
#         date mpressure mxtemp
#2  2008-01-02    1025.6   16.0
#3  2008-01-03    1023.6   18.1
#4  2008-01-04    1021.8   18.4
#5  2008-01-05    1020.1   20.9
#9  2008-01-09    1015.3   24.5
#10 2008-01-10    1014.3   21.8
#11 2008-01-11    1012.9   23.4

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