Import files using key words

问题:

I would like to import image files using parts of their names. I have 100 .tif images whose names are composed of 3 different elements, say Ai, Bi and Ci in such way: "A1 B1 C1.tif", "A1 B2 C1.tif", "A1 B1 C2.tif", "A2 B1 C1.tif"... I defined Ai, Bi and Ci at the beginning of the code, and want to call the file that contains these 3 elements.

I have tried options that have no chance to be correct, but cannot find anything better:

f = readTiff(Ai Bi Ci)
f = readTiff(Ai, Bi, Ci)
f = readTiff("Ai Bi Ci")

and the same using readImage and file.name. The getwd gives the correct path. Thank you in advance.

回答1:

You can use the paste command to glue strings together.

# for i for A, j for B selection and k for C selection
my.filename <- paste("A", i, " B", j, " C", k, ".tif", sep = "")

so if you wanted to import A1 B2 C2.tif

i <- 1
j <- 2
k <- 2
my.filename <- paste("A", i, " B", j, " C", k, ".tif", sep = "")

Note paste0 defaults to sep = "" so paste0("A", i, " B", j, " C", k, ".tif")

results in my.filename

 1)  "A1 B2 C2.tif"

if you are working with paths then:

my.filename <- paste("A", i, " B", j, " C", k, ".tif", sep = "")
my.path <- getwd() # or set this
readTiff(file.path(my.path, my.filename))

If you want to work through all combinations of i, j, k in loops then you can use file.exists and if it does then import it.

Note: Which package are you using for readTiff? Do not forget to make sure this package is loaded in your script, with library(thispackage) if you are getting "object not found" errors.