Support csv file reading and writing in loadtxt and savetxt.

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
 
@@ -52,7 +52,8 @@ Experimental
 
 ### Description
 
-Returns the unit number of a file opened to read, to write, or to read and write. The file might be a text file or a binary file. All files are opened using a streamed access.
+Returns the unit number of a file opened to read, to write, or to read and write. The file might be a text file or a binary file.
+Text files are opened using a sequential access, while binary files are opened using a streamed access.
 
 ### Syntax
 
@@ -105,14 +106,16 @@ 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`.

doc/specs/stdlib_math.md

@@ -427,7 +427,7 @@ Experimental
 
 Elemenal function.
 
-### Description
+#### Description
 
 `deg2rad` converts phase angles from degrees to radians.
 

doc/specs/stdlib_sparse.md

@@ -178,7 +178,7 @@ Type-bound procedures to enable requesting data from a sparse matrix.
 
 `v` : Shall be a `real` or `complex` value in accordance to the declared sparse matrix object. If the `ij` tuple is within the sparse pattern, `v` contains the value in the data buffer. If the `ij` tuple is outside the sparse pattern, `v` is equal `0`. If the `ij` tuple is outside the matrix pattern `(nrows,ncols)`, `v` is `NaN`.
 
-## Example
+### Example
 ```fortran
 {!example/linalg/example_sparse_data_accessors.f90!}
 ```
@@ -257,7 +257,7 @@ This module provides facility functions for converting between storage formats.
 
 `chunk`, `optional`: chunk size, only valid in the case of a `SELLC` matrix, by default it will be taken from the `SELLC` default attribute chunk size. It is an `intent(in)` argument.
 
-## Example
+### Example
 ```fortran
 {!example/linalg/example_sparse_from_ijv.f90!}
 ```
@@ -358,7 +358,7 @@ If the `diagonal` array has not been previously allocated, the `diag` subroutine
 
 `coo` : Shall be a `COO` type of `real` or `complex` type. It is an `intent(out)` argument.
 
-## Example
+### Example
 ```fortran
 {!example/linalg/example_sparse_spmv.f90!}
 ```

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

@@ -59,13 +59,15 @@ module stdlib_io
     !> Format string for quadruple precision real numbers
     FMT_REAL_QP = '(es44.35e4)', &
     !> Format string for single precision complex numbers
-    FMT_COMPLEX_SP = '(es15.8e2,1x,es15.8e2)', &
+    FMT_COMPLEX_SP = '(es15.08e2,1x,es15.08e2)', &
     !> Format string for double precision complex numbers
     FMT_COMPLEX_DP = '(es24.16e3,1x,es24.16e3)', &
     !> Format string for extended double precision complex numbers
     FMT_COMPLEX_XDP = '(es26.18e3,1x,es26.18e3)', &
     !> Format string for quadruple precision complex numbers
     FMT_COMPLEX_QP = '(es44.35e4,1x,es44.35e4)'
+  !> Default delimiter for loadtxt, savetxt and number_of_columns
+  character(len=1), parameter :: delimiter_default = " "
 
   public :: FMT_INT, FMT_REAL_SP, FMT_REAL_DP, FMT_REAL_XDP, FMT_REAL_QP
   public :: FMT_COMPLEX_SP, FMT_COMPLEX_DP, FMT_COMPLEX_XDP, FMT_COMPLEX_QP
@@ -103,7 +105,7 @@ 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.
@@ -123,7 +125,9 @@ 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_
+      character(len=1) :: delimiter_
       !!
       !! Example
       !! -------
@@ -142,11 +146,13 @@ contains
       !!     ...
       !!
       integer :: s
-      integer :: nrow, ncol, i, ios, skiprows_, max_rows_
+      integer :: nrow, ncol, i, j, ios, skiprows_, max_rows_, istart, iend
+      character(len=:), allocatable :: line, iomsg_
       character(len=1024) :: iomsg, msgout
 
       skiprows_ = max(optval(skiprows, 0), 0)
       max_rows_ = optval(max_rows, -1)
+      delimiter_ = optval(delimiter, delimiter_default)
 
       s = open(filename)
 
@@ -157,12 +163,13 @@ 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
       #:endif
 
       allocate(d(max_rows_, ncol))
+      if (max_rows_ == 0 .or. ncol == 0) return
 
       do i = 1, skiprows_
         read(s, *, iostat=ios, iomsg=iomsg)
@@ -186,15 +193,44 @@ contains
 
       if ( fmt_ == '*' ) then
         ! Use list directed read if user has specified fmt='*'
-        do i = 1, max_rows_
-          read (s,*,iostat=ios,iomsg=iomsg) d(i, :)
-
-          if (ios/=0) then 
-             write(msgout,2) trim(iomsg),size(d,2),i,trim(filename)
-             call error_stop(msg=trim(msgout))
-          end if          
-
-        enddo
+        if (is_blank(delimiter_) .or. delimiter_ == ",") then
+          do i = 1, max_rows_
+            read (s,*,iostat=ios,iomsg=iomsg) d(i, :)
+
+            if (ios/=0) then 
+              write(msgout,2) trim(iomsg),size(d,2),i,trim(filename)
+              call error_stop(msg=trim(msgout))
+            end if          
+
+          enddo
+        ! Otherwise read each value separately
+        else
+          do i = 1, max_rows_
+            call get_line(s, line, ios, iomsg_)
+            if (ios/=0) then 
+               write(msgout,2) trim(iomsg_),size(d,2),i,trim(filename)
+               call error_stop(msg=trim(msgout))
+            end if
+
+            istart = 0
+            do j = 1, ncol - 1
+              iend = index(line(istart+1:), delimiter_)
+              read (line(istart+1:istart+iend-1),*,iostat=ios,iomsg=iomsg) d(i, j)
+              if (ios/=0) then 
+                 write(msgout,2) trim(iomsg),size(d,2),i,trim(filename)
+                 call error_stop(msg=trim(msgout))
+              end if
+              istart = istart + iend
+            end do
+
+            read (line(istart+1:),*,iostat=ios,iomsg=iomsg) d(i, ncol)
+            if (ios/=0) then 
+               write(msgout,2) trim(iomsg),size(d,2),i,trim(filename)
+               call error_stop(msg=trim(msgout))
+            end if          
+
+          enddo
+        end if
       else
         ! Otherwise pass default or user specified fmt string.
         do i = 1, max_rows_
@@ -217,7 +253,7 @@ 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 +263,7 @@ 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 +273,26 @@ 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, delimiter_default)
+      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_${k1}$(1:11)//delim_str//FMT_COMPLEX_${k1}$(14:23)//",:,"//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 +312,22 @@ 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, delimiter_default)
 
     rewind(s)
 
@@ -291,12 +340,23 @@ 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_ == delimiter_default) 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
@@ -400,14 +460,14 @@ contains
     select case (mode_(3:3))
     case('t')
       form_='formatted'
+      access_='sequential'
     case('b')
       form_='unformatted'
+      access_ = 'stream'
     case default
       call error_stop("Unsupported mode: "//mode_(3:3))
     end select
 
-    access_ = 'stream'
-
     if (present(iostat)) then
       open(newunit=u, file=filename, &
           action = action_, position = position_, status = status_, &

test/io/test_loadtxt.f90

@@ -47,6 +47,14 @@ 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
+            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 +82,14 @@ 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
+            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 +174,10 @@ 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 +292,14 @@ 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
+            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