r - Divide all columns by the value from the 2nd column - apply for all rows

Question

I have such data:

dput(tbl_data[1:5])
structure(list(Name = c("Mark", "Anders", "Tom", "Vin", "Marcel", 
"Tyta", "Gerta", "Moses", "Hank", "Rita", "Margary"), Col = c(1769380097.5, 
1444462500, 1499146687.5, 1276309375, 22279500, 3114023471, 2961012500, 
3978937423.5, 1703925000, 1838885550, 1483386250), dKO1 = c(1534931323.07692, 
1794881375, 2292661687.5, 855786250, 21915500, 3056061512.25, 
3581940000, 3766909703.25, 2043300000, 2135859875, 1482031250
), dKO2 = c(1628137500, 1781982737.5, 1659391250, 741220687.5, 
41242000, 2833327766.38514, 3675450000, 3592650662.5, 1586512500, 
1934575000, 1467271250), sdi1 = c(1545572702.88461, 1748600000, 
1745026687.5, 1556481250, NaN, 3551716021.25, 3108137500, 3718036445, 
1380278750, 2217526000, 1026813750)), .Names = c("Name", "Col", 
"dKO1", "dKO2", "sdi1"), row.names = c(29L, 30L, 1278L, 1295L, 
1296L, 1297L, 1298L, 1307L, 1642L, 1674L, 1754L), class = "data.frame")

As the title states I would like to divide all the columns in a row by the value from 2nd column. First column should be ignored because it's a name. Of course first column can be deleted and put as a row names if it makes life easier.

I would like to apply it for all the rows in this data frame.

I quite simple but my mind is not working properly today.

Answer 1

You can use function sweep :

tbl_data[, -(1:2)] <- sweep(tbl_data[, -(1:2)], 1, tbl_data[, 2], "/")

tbl_data
        Name        Col      dKO1      dKO2      sdi1
29      Mark 1769380098 0.8674967 0.9201740 0.8735108
30    Anders 1444462500 1.2425947 1.2336649 1.2105541
1278     Tom 1499146688 1.5293111 1.1068905 1.1640133
1295     Vin 1276309375 0.6705163 0.5807531 1.2195172
1296  Marcel   22279500 0.9836621 1.8511187       NaN
1297    Tyta 3114023471 0.9813868 0.9098608 1.1405553
1298   Gerta 2961012500 1.2097011 1.2412815 1.0496874
1307   Moses 3978937424 0.9467125 0.9029171 0.9344295
1642    Hank 1703925000 1.1991725 0.9310929 0.8100584
1674    Rita 1838885550 1.1614969 1.0520367 1.2059076
1754 Margary 1483386250 0.9990865 0.9891363 0.6922093