r - RMySQL: Transforming extracted data -

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i trying extract numeric data database columns have been set varchar(100). data in relevant columns numeric there shouldn't problem extracting data formatted integer. there nice way in r?

here got:

m_df <- dbgetquery(conn, paste("select ", direc, " position, ", power, " power ", table,                       " d left join files f on f.id=d.fileid parc='", parc,                       "' , timestamp >= '", w_date[1], "' , timestamp <= '", w_date[2],                       "' , plantnumber = ", w_mach, sep=""))

executing following:

sum(m_df$power)

produces error:

error in sum(m_df$power) : invalid 'type' (character) of argument

performing:

str(m_df)

generates:

 'data.frame':   4317 obs. of  2 variables:  $ position: chr  "280" "281" "288" "294" ...  $ power   : chr  "294" "342" "324" "284" ...

you trying sum characters , r saying "whaaaa?". little snippet follows reproduces error.

(x.char <- sum(c("1", "2", "3")))  error in sum(c("1", "2", "3")) : invalid 'type' (character) of argument (sum(as.numeric(x.char)))  [1] 6

run as.numeric function on data.frame , you're go.


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