Add the delimiter argument to the loadtxt and savetxt functions.

Author: zoziha

doc/specs/stdlib_io.md

@@ -17,7 +17,7 @@ Loads a rank-2 `array` from a text file.
 
 ### Syntax
 
-`call ` [[stdlib_io(module):loadtxt(interface)]] `(filename, array [, skiprows] [, max_rows] [, fmt])`
+`call ` [[stdlib_io(module):loadtxt(interface)]] `(filename, array [, skiprows] [, max_rows] [, fmt] [, delimiter])`
 
 ### Arguments
 
@@ -31,7 +31,7 @@ Loads a rank-2 `array` from a text file.
 
 `fmt` (optional): Fortran format specifier for the text read.  Defaults to the write format for the data type.  Setting fmt='*' will specify list directed read.   
 
-
+`delimiter` (optional): Shall be a character expression of length 1 that contains the delimiter used to separate the columns. The default is `' '`.
 
 ### Return value
 
@@ -105,14 +105,16 @@ Saves a rank-2 `array` into a text file.
 
 ### Syntax
 
-`call ` [[stdlib_io(module):savetxt(interface)]] `(filename, array)`
+`call ` [[stdlib_io(module):savetxt(interface)]] `(filename, array [, delimiter])`
 
 ### Arguments
 
 `filename`: Shall be  a character expression containing the name of the file that will contain the 2D `array`.
 
 `array`: Shall be a rank-2 array of type `real`, `complex` or `integer`.
 
+`delimiter` (optional): Shall be a character expression of length 1 that contains the delimiter used to separate the columns. The default is `' '`.
+
 ### Output
 
 Provides a text file called `filename` that contains the rank-2 `array`.

example/io/example.csv

@@ -0,0 +1,3 @@
+ 1.00000000E+00, 1.00000000E+00
+ 1.00000000E+00, 1.00000000E+00
+ 1.00000000E+00, 1.00000000E+00

example/io/example_loadtxt.f90

@@ -6,4 +6,7 @@ program example_loadtxt
 
   ! Can also use list directed format if the default read fails.
   call loadtxt('example.dat', x, fmt='*')
+
+  call loadtxt('example.csv', x, delimiter=',')
+
 end program example_loadtxt

example/io/example_savetxt.f90

@@ -3,4 +3,5 @@ program example_savetxt
   implicit none
   real :: x(3, 2) = 1
   call savetxt('example.dat', x)
+  call savetxt('example.csv', x, delimiter=',')
 end program example_savetxt

src/stdlib_io.fypp

@@ -103,7 +103,7 @@ module stdlib_io
 contains
 
   #:for k1, t1 in KINDS_TYPES
-    subroutine  loadtxt_${t1[0]}$${k1}$(filename, d, skiprows, max_rows, fmt)
+    subroutine  loadtxt_${t1[0]}$${k1}$(filename, d, skiprows, max_rows, fmt, delimiter)
       !! version: experimental
       !!
       !! Loads a 2D array from a text file.
@@ -123,6 +123,7 @@ contains
       !! The default value is -1.
       integer, intent(in), optional :: max_rows
       character(len=*), intent(in), optional :: fmt
+      character(len=1), intent(in), optional :: delimiter
       character(len=:), allocatable :: fmt_
       !!
       !! Example
@@ -157,9 +158,11 @@ contains
 
       ! determine number of columns
       ncol = 0
-      if ( skiprows_ < nrow ) ncol = number_of_columns(s, skiprows=skiprows_)
+      if ( skiprows_ < nrow ) ncol = number_of_columns(s, skiprows=skiprows_, delimiter=delimiter)
       #:if 'complex' in t1
-      ncol = ncol / 2
+      if (present(delimiter)) then
+        if (is_blank(delimiter)) ncol = ncol / 2
+      end if
       #:endif
 
       allocate(d(max_rows_, ncol))
@@ -217,7 +220,7 @@ contains
 
 
   #:for k1, t1 in KINDS_TYPES
-    subroutine savetxt_${t1[0]}$${k1}$(filename, d)
+    subroutine savetxt_${t1[0]}$${k1}$(filename, d, delimiter)
       !! version: experimental
       !!
       !! Saves a 2D array into a text file.
@@ -227,6 +230,7 @@ contains
       !!
       character(len=*), intent(in) :: filename  ! File to save the array to
       ${t1}$, intent(in) :: d(:,:)           ! The 2D array to save
+      character(len=1), intent(in), optional :: delimiter  ! Column delimiter. Default is a space.
       !!
       !! Example
       !! -------
@@ -236,17 +240,27 @@ contains
       !! call savetxt("log.txt", data)
       !!```
       !!
-
+      
       integer :: s, i, ios
+      character(len=1) :: delimiter_
+      character(len=3) :: delim_str
+      character(len=:), allocatable :: fmt_
       character(len=1024) :: iomsg, msgout
+
+      delimiter_ = optval(delimiter, " ")
+      delim_str = "'"//delimiter_//"'"
+      #:if 'real' in t1
+        fmt_ = "(*"//FMT_REAL_${k1}$(1:len(FMT_REAL_${k1}$)-1)//",:,"//delim_str//"))"
+      #:elif 'complex' in t1
+        fmt_ = "(*"//FMT_COMPLEX_${k1}$(1:len(FMT_COMPLEX_${k1}$)-1)//",:,"//delim_str//"))"
+      #:elif 'integer' in t1
+        fmt_ = "(*"//FMT_INT(1:len(FMT_INT)-1)//",:,"//delim_str//"))"
+      #:endif
+
       s = open(filename, "w")
       do i = 1, size(d, 1)
-        #:if 'real' in t1
-          write(s, "(*"//FMT_REAL_${k1}$(1:len(FMT_REAL_${k1}$)-1)//",:,1x))", &
-        #:elif 'complex' in t1
-          write(s, "(*"//FMT_COMPLEX_${k1}$(1:len(FMT_COMPLEX_${k1}$)-1)//",:,1x))", &
-        #:elif 'integer' in t1
-          write(s, "(*"//FMT_INT(1:len(FMT_INT)-1)//",:,1x))", &
+        #:if 'real' in t1 or 'complex' in t1 or 'integer' in t1
+          write(s, fmt_, &
         #:else
           write(s, *, &
         #:endif
@@ -266,19 +280,22 @@ contains
   #:endfor
 
 
-  integer function number_of_columns(s, skiprows)
+  integer function number_of_columns(s, skiprows, delimiter)
     !! version: experimental
     !!
     !! determine number of columns
     integer,intent(in) :: s
     integer, intent(in), optional :: skiprows
+    character(len=1), intent(in), optional :: delimiter
 
     integer :: ios, skiprows_, i
     character :: c
     character(len=:), allocatable :: line
-    logical :: lastblank
+    character(len=1) :: delimiter_
+    logical :: last_delim
 
     skiprows_ = optval(skiprows, 0)
+    delimiter_ = optval(delimiter, " ")
 
     rewind(s)
 
@@ -291,12 +308,23 @@ contains
     call get_line(s, line, ios)
     if (ios/=0 .or. .not.allocated(line)) return
 
-    lastblank = .true.
-    do i = 1,len(line)
-      c = line(i:i)
-      if (lastblank .and. .not. is_blank(c)) number_of_columns = number_of_columns + 1
-      lastblank = is_blank(c)
-    end do
+    last_delim = .true.
+    if (delimiter_ == " ") then
+      do i = 1,len(line)
+        c = line(i:i)
+        if (last_delim .and. .not. is_blank(c)) number_of_columns = number_of_columns + 1
+        last_delim = is_blank(c)
+      end do
+    else
+      do i = 1,len(line)
+        if (line(i:i) == delimiter_) number_of_columns = number_of_columns + 1
+      end do
+      if (number_of_columns == 0) then
+        if (len_trim(line) /= 0) number_of_columns = 1
+      else
+        number_of_columns = number_of_columns + 1
+      end if
+    end if
     rewind(s)
 
   end function number_of_columns

test/io/test_loadtxt.f90

@@ -47,6 +47,10 @@ subroutine test_loadtxt_int32(error)
             call loadtxt('test_int32.txt', expected, fmt='*')
             call check(error, all(input == expected),'User specified list directed read faile')
             if (allocated(error)) return
+            call savetxt('test_int32.txt', input, delimiter=',')
+            call loadtxt('test_int32.txt', expected, delimiter=',')
+            call check(error, all(input == expected),'User specified delimiter read failed')
+            if (allocated(error)) return
         end do
 
     end subroutine test_loadtxt_int32
@@ -74,6 +78,10 @@ subroutine test_loadtxt_sp(error)
             call loadtxt('test_sp.txt', expected, fmt="(*"//FMT_REAL_sp(1:len(FMT_REAL_sp)-1)//",1x))")
             call check(error, all(input == expected),'User specified format failed')
             if (allocated(error)) return
+            call savetxt('test_sp.txt', input, delimiter=',')
+            call loadtxt('test_sp.txt', expected, delimiter=',')
+            call check(error, all(input == expected),'User specified delimiter read failed')
+            if (allocated(error)) return
         end do
 
     end subroutine test_loadtxt_sp
@@ -158,6 +166,10 @@ subroutine test_loadtxt_dp(error)
             call loadtxt('test_dp.txt', expected, fmt="(*"//FMT_REAL_dp(1:len(FMT_REAL_dp)-1)//",1x))")
             call check(error, all(input == expected),'User specified format failed')
             if (allocated(error)) return
+            call savetxt('test_dp.txt', input, delimiter=',')
+            call loadtxt('test_dp.txt', expected, delimiter=',')
+            call check(error, all(input == expected),'User specified delimiter read failed')
+            if (allocated(error)) return
         end do
 
     end subroutine test_loadtxt_dp
@@ -272,6 +284,10 @@ subroutine test_loadtxt_complex(error)
             call loadtxt('test_complex.txt', expected, fmt="(*"//FMT_COMPLEX_dp(1:len(FMT_COMPLEX_dp)-1)//",1x))")
             call check(error, all(input == expected))
             if (allocated(error)) return
+            call savetxt('test_complex.txt', input, delimiter=',')
+            call loadtxt('test_complex.txt', expected, delimiter=',')
+            call check(error, all(input == expected))
+            if (allocated(error)) return
         end do
 
     end subroutine test_loadtxt_complex