Question

I have several txt files with 3 columns in each files like this:
file 1:

ProbeID X_Signal_intensity X_P-Value   
xxx         2.34          .89
xxx         6.45          .04 
xxx         1.09          .91  
xxx         5.87          .70
.            .            . 
.            .            .
.            .            .     

file 2:

ProbeID Y_Signal_intensity Y_P-Value   
xxx         1.4             .92
xxx         2.55            .14 
xxx         4.19            .16  
xxx         3.47            .80
.            .               . 
.            .               .
.            .               . 

file 3:

ProbeID Z_Signal_intensity Z_P-Value   
xxx         9.40             .82
xxx         1.55            .04 
xxx         3.19            .56  
xxx         2.47            .90
.            .               . 
.            .               .
.            .               . 

In all the above files the values of ProbeID column are identical but not the other columns.Now I want to combine the all the above files using a for-loop into a single file like this:

ProbeID X_intensity X_P-Value   Y_intensity Y_P-Value   Z_intensity Z_P-Value     
xxx      2.34          .89       1.4             .92     9.40            .82
xxx      6.45          .04       2.55            .14     1.55            .04
xxx      1.09          .91       4.19            .16     3.19            .56
xxx      5.87          .70       3.47            .80     2.47            .90

Please do help me.

Answer 1

My approach is to read the files into data.frames

see help(read.delim) for reading modes.

After you have your three data.frames you can use

total <- merge(dataframeA,dataframeB,by="ProbeID")

look here http://www.statmethods.net/management/merging.html for documentation.