[R] HELP!! how to remove 10% of data randomly in R

[Nordlund, Dan (DSHS/RDA)]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Eugenie
> Sent: Wednesday, October 31, 2012 5:42 AM
> To: r-help at r-project.org
> Subject: Re: [R] HELP!! how to remove 10% of data randomly in R
> 
>   tDate tTime    O3   No2 Temp Sun Wspeed Wdirect Hum Indicator
> 1    19980101  2400 0.065 0.036 31.4 765    9.9     351  NA         1
> 2    19980102  2400 0.053 0.025 31.8 624    7.7     351  NA         1
> 3    19980103  2400 0.027 0.033 31.5 852    8.8     331  NA         2
> 4    19980104  2400 0.034 0.023 30.7 679    7.0     338  NA         2
> 5    19980105  2400 0.019 0.016 28.1 376    9.6     354  NA         1
> 6    19980106  2400 0.021 0.018 29.9 603    9.3     356  NA         1
> 7    19980107  2400 0.026 0.047 31.2 857   10.7     336  NA         1
> 8    19980108  2400 0.024 0.014 31.1 635    7.8     330  NA         1
> 9    19980109  2400 0.058 0.033 32.5 742   10.7     334  NA         1
> 10   19980110  2400 0.026 0.032 33.9 923   10.6     347  NA         2
> 11   19980111  2400 0.064 0.034 32.5 751    6.3     355  NA         2
> 12   19980112  2400 0.066 0.034 33.3 697    8.5     319  NA         1
> 13   19980113  2400 0.026 0.030 33.4 992   12.5     341  NA         1
> 14   19980114  2400 0.101 0.028 33.8 705    8.7     349  NA         1
> 15   19980115  2400 0.069 0.030 33.3 718   11.4     348  NA         1
> 16   19980116  2400 0.054 0.026 33.4 639   10.9     354  NA         1
> 17   19980117  2400 0.090 0.039 33.1 653   13.2     342  NA         2
> 18   19980118  2400 0.048 0.017 33.2 825   10.8     323  NA         2
> 19   19980119  2400 0.038 0.027 33.7 984   10.3     353  NA         1
> 20   19980120  2400 0.026 0.032 34.2 994   15.0     357  NA         1
> 21   19980121  2400 0.065 0.044 33.8 999   17.5     343  NA         1
> 22   19980122  2400 0.046 0.024 33.5 931   10.1     332  NA         1
> 23   19980123  2400 0.050 0.041 33.9 881   11.3     353  NA         1
> 24   19980124  2400 0.036 0.027 33.8 877    9.1     328  NA         2
> 25   19980125  2400 0.043 0.021 33.2 777   10.5     340  NA         2
> 26   19980126  2400 0.029 0.016 33.1 999   14.1     341  NA         1
> 27   19980127  2400 0.033 0.030 33.9 943   12.9     344  NA         1
> 28   19980128  2400 0.040 0.022 33.7 805   12.6     354  NA         1
> 29   19980129  2400 0.029 0.015 30.2 512    7.4     356  NA         1
> 30   19980130  2400 0.027 0.013 31.7 656   13.9     349  NA         1
> 
> 
> 
> if given data like this,how to remove the data in
> O3,NO2,sun,temp,wspeed
> randomly??(missing values in these rows & columns)
> 
> 

If your data frame is called dat, then something like this may do what you want, but since you haven't given an example of what you want the output to look like I am only guessing.

dat[sample(1:30,5),3:8] <- NA


hope this is helpful,

Dan

Daniel J. Nordlund
Olympia, WA 98504-5204