I have a table with lots of data and need the variable type of specific columns. The function sapply brings the variable type for ALL columns while I want specific ones. Can you help? Thanks!
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1You can select a single column with `[[` (with a quoted column name or string) or `$` (unquoted column name). E.g., `typeof(your_data[["specific column"]])` or `typeof(your_data$specific_column)`. Or whatever function you want, `class`, `mode`, `sum`, `mean`, ... – Gregor Thomas Sep 13 '19 at 19:23
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It's easier to help you if you include a simple [reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) with sample input and desired output that can be used to test and verify possible solutions. – MrFlick Sep 13 '19 at 19:41
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You can use:
a <- data.frame(a = c('a', 'b'), b = c(1L, 2L), c = c(1.,2.), d = c(TRUE, FALSE),
stringsAsFactors = FALSE)
# populate with specific column names
col_names <- c('a','b')
sapply(a[,col_names], typeof)
sapply(a[,col_names], class)
# ... and other functions
slava-kohut
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Supposing you have:
x<-data.frame(column1=c("a","b","c"),column2=c(1,2,3))
If I understand your question, you can do:
class(x[,2])
to determine the class of the second column.
DrDominio
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Another option is using the **$** operator: `class(x$column2)` – Orlando Sabogal Sep 13 '19 at 19:59