consecutively subtracting columns in data.table

Suppose I have the following data.table:

 player_id prestige_score_0 prestige_score_1 prestige_score_2 prestige_score_3 prestige_score_4
   1:    100284     0.0001774623     2.519792e-03     5.870781e-03     7.430179e-03     7.937716e-03
   2:    103819     0.0001774623     1.426482e-03     3.904329e-03     5.526974e-03     6.373850e-03
   3:    100656     0.0001774623     2.142518e-03     4.221423e-03     5.822705e-03     6.533448e-03
   4:    104745     0.0001774623     1.084913e-03     3.061197e-03     4.383649e-03     5.091851e-03
   5:    104925     0.0001774623     1.488457e-03     2.926728e-03     4.360301e-03     5.068171e-03

And I want to find the difference between values in each column starting from column prestige_score_0

In one step it should look like this: df[,prestige_score_0] - df[,prestige_score_1]

How can I do it in data.table(and save this differences as data.table and keep player_id as well)?

This is how you can do this in a tidy way:

# make it tidy
df2 <- melt(df, 
            id = "player_id", 
            variable.name = "column_name", 
            value.name = "prestige_score")  
# extract numbers from column names
df2[, score_number := as.numeric(gsub("prestige_score_", "", column_name))]
# compute differences by player
df2[, diff := prestige_score - shift(prestige_score, n = 1L, type = "lead"),
    by = player_id]

# if necessary, reshape back to original format
dcast(df2, player_id ~ score_number, value.var = c("prestige_score", "diff"))

Developing Web Applications with Visual Basic.NET and ASP.NET, For example, suppose you need a Contacts DataTable to have a column with a full name, but the You can also do calculations in a derived column, including addition, subtraction, and so on. Examining Different Versions of Data in a Row​. consecutively subtracting columns in data.table. Ask Question. Asked 2 years, 3 months ago. Active 1 year, 4 months ago. Viewed 601 times. 0. Suppose I have the following data.table: player_id prestige_score_0 prestige_score_1 prestige_score_2 prestige_score_3 prestige_score_4 1: 100284 0.0001774623 2.519792e-03 5.870781e-03 7.430179e-03 7.937716e-03 2: 103819 0.0001774623 1.426482e-03 3.904329e-03 5.526974e-03 6.373850e-03 3: 100656 0.0001774623 2.142518e-03 4.221423e-03 5.822705e-03 6.

you can subtract a whole dt with a shifted version of itself

dt = data.table(id=c("A","B"),matrix(rexp(10, rate=.1), ncol=5))
dt_shift = data.table(id=dt[,id], dt[, 2:(ncol(dt)-1)] - dt[,3:ncol(dt)])

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You could use a for loop -

for(i in c(1:(ncol(df)-1)){
    df[, paste0("diff_", i-1, "_", i)] = df[, paste0("prestige_score_", i-1)] - 
                                              df[, paste0("prestige_score_", i)]
}

This might not be the most efficient if you have a lot of columns though.

How to subtract in Excel: cells, columns, percentages, dates and times, See how to subtract cells and entire columns, text of one cell from another cell, Applied to our sample data set, it takes the following shape:. Subtract Multiple Cells Using Formula You need an absolute cell reference for subtracting numbers with a number. Make the cell reference of the deduction number absolute, to prevent the cell address changing when the formula is copied.

How to Do Simple Table Manipulations With R in Q, R is not just a tool for the data science elite. If there are two dimensions to the source table (rows and columns) we use items But likewise, you can subtract one variable from another to produce a new variable (eg: x – y = z). The variable isn't a single number, but rather 6 consecutive numbers, each  Pandas dataframe.subtract() function is used for finding the subtraction of dataframe and other, element-wise. This function is essentially same as doing dataframe - other but with a support to substitute for missing data in one of the inputs. Syntax: DataFrame.subtract(other, axis=’columns’, level=None, fill_value=None)

How to subtract one cell with previous cell in the table in matlab and , How to subtract one cell with previous cell in the table in matlab and do it consecutively until I also want to do it consecutively until the last row. diff() will give you the difference between rows of each column in your table, t. pandas.DataFrame.subtract¶ DataFrame.subtract (self, other, axis = 'columns', level = None, fill_value = None) [source] ¶ Get Subtraction of dataframe and other, element-wise (binary operator sub). Equivalent to dataframe-other, but with support to substitute a fill_value for missing data in one of the inputs. With reverse version, rsub.

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