undefined columns selected problem when trying to run this code [closed] - r

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I am trying to use the air dataset from the dummies package.
I tried:
library(dummies)
dumair<-air[c(5:18)]
but that throws the following error:
Error in `[.data.frame`(air, c(5:18)) : undefined columns selected
How can I overcome this?

You need to specify which columns you want to select. When selecting rows and columns from a dataframe, you need to specify them like this:
df[rows, columns]
If you need all columns, leave the "columns" field empty. Same if you want all rows but only some columns!
I believe you want to select all columns, but only the rows from 5 to 18, right?
So doing:
dumair <- air[c(5:18), ]
Should work!

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r function for counting specific row of 2 columns [closed]

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I need help how to compare 2 columns in r studio but only in the first 5 observations
code used first was
damgeByage<-table(test$Vehicle_Age,test$Vehicle_Damage)
damgeByage
which give me all 186 observation but only want the first 10 oobservation of both columns
I
We can subset the data with row index
table(test[1:10, c("Vehicle_Age", "Vehicle_Damage")])
akrun's answer works or you can also use:
table(test$Vehicle_Age[1:10],test$Vehicle_Damage[1:10])
the table is also subsettable if you just wanted the first 10 rows of the results:
damgeByage<-table(test$Vehicle_Age,test$Vehicle_Damage)
damgeByage[1:10,]

Object not detected in R [closed]

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When I use correlation function in RstudioThis I get below error message:
The dataset that I have imported is show below and V1,V2 are given by default to the columns:
There are two ways:
1) Attaching the data:
attach(data1)
And then this code should work:
cor(V1, V2)
2) Using $ for accesing columns in a dataframe
cor(data1$V1, data1$V2)
So, if I got you correctly, you want to find correlation between variables V1 and V2 in the dataframe data1. To refer to the column in the dataframe a $ sign is used. Then your code will look like:
cor(data1$V1,data1$V2)
or, if you want, you can also use with() function, which would narrow down the namespace to particular dataframe data1:
with(data1, cor(V1, V2))

Re-labeling columns in R [closed]

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I need to replace number values with something that makes more sense to the reader.
Value “-0.95197” represents “18-24” age group in the given table.
What would be the best way to go about this for all columns?
Your question is a little unclear. Are you trying to rename the header of each column in a data.frame? If so, try this, where df is the name of your data.frame. You need one piece of text for each column.
names(df) <- c("your", "header", "names", "go", "here")
If this is not what you want, then you need to provide more info.

Dataframe convert factors to numerical error [closed]

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Closed 5 years ago.
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I am trying to convert factors from a data-frame to numeric using the commands
data[] <- lapply (data, function(x) as.numeric(as.character(x))
But it keeps asking me for more coding. What am I doing wrong?
The data-frame is named data and it consists of 50 rows and 2 columns. Will this command change every variable in numeric right? Or shall I do something else?
screenshot after using 'dput' at http://imgur.com/Sde9QSk.png
Shouldn't you add ) at the end of your code?

apply function doesn't work [closed]

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I have a data frame that has some empty entries. I set the
options(stringsAsFactors = FALSE)
so that I can change the empty cells. I then wrote the following code:
apply(my_data[,6:65],2, function(x) x[which(x=='')]<-0)
, hoping that it replaces all the empty cells with zeros. But it isn't working!
Note that my_data has 65 columns and columns 1:5 contain string.
Thanks in advance
No need to use apply, just use [<- with logical indexing
my_data[my_data==""] <- 0

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