File Input/Output Tips

Visit the Coyote Plot Gallery for additional information regarding reading and writing data in IDL.

Scientific Data Formats

• I can't make heads or tails of the IDL HDF documentation. Can you help!?
• Can I write a DICOM file in IDL?
• Is there a way to handle an HDF file open failure more gracefully than “Sorry, Charlie?”
• How do I write a structure to an HDF5 file?
• Is there an easy way to browse and read netCDF or HDF files in IDL?
• Yikes! How do I read and write string arrays to netCDF files?
• Can you explain the purpose of the Count, Offset, and Stride keywords in reading a netCDF variable?
• Why can't I take my netCDF file out of “define” mode?
• Do you have any tools for browsing MABEL Lidar data?
• How can I write a KML file to display an IDL image in Google Earth?
• Can you show me how to browse and visualize an HDF-EOS2 grid file?
• How can I write fixed length strings into netCDF files?
• How can I convert time strings to the seconds required for CF-compliant netCDF files?

Standard File Formats

• How do I create a color JPEG file from a 2D image?
• How do I create MPEG movies in IDL?
• How do I create a color TIFF image?
• How do I create a color JPEG image?
• Is there a size limitation to IDL generated MPEG files?
• How do I set my MPEG file frame rate to one frame per second?
• Can I make a JPEG file of a line plot without opening a graphics window?
• What do you know about working with AVI files in IDL?
• How can I create PDF files from within IDL?
• How can I determine if my TIFF file is georeferenced?
• How can I create a color (JPEG, TIFF, PNG, BMP) image from an IDL graphics window?
• My colleague produces GIF output in IDL, but I can't. What's up with that!?
• How can I make a PNG image with an alpha channel?
• Why does the PNG image I created render darker then the original PNG image?
• How do I create PDF files using Coyote Graphics?
• Create PostScript, PDF, and raster files from basic Coyote Graphics commands!
• Why can't I read MrSID files on my computer?
• How can I create an AVI movie in IDL?
• How can I create an MPG-4 video annimation in IDL?
• Yikes! Did gzip just eat my file extension?

General I/O Tips

• How can I read an ASCII data file that has a header and three columns of data?
• How can I work with unsigned integers in IDL?
• Why can't I read from a file into a subscripted array?
• People talk about "little indian" and "big indian" machines. What in the world are they talking about!?
• How do I count the number of rows in a text file?
• How can I count the number of columns in a text file?
• When I read a new variable READF skips to the start of a new line. How can I prevent that?
• The Findfile function didn't find all the files on my UNIX machine. What is going on?
• How do I write my IDL array out as a comma separated value file I can open in my spreadsheet?
• How do I print the contents of a graphics window?
• I just want to create and print a text file from within IDL. Can this be done?
• What is the best way to make a scientific animation in IDL?
• How do I create a PostScript file of object graphic output?
• I'm having trouble storing an associated file variable in a structure. Why?
• How do I separate the file name from the file path returned by Dialog_Pickfile?
• Why do I have memory leaks from IDL's file reading objects?
• How can I make an IDL plot with a transparent background for inclusion in a PowerPoint slide?
• I can't open a 2 GByte file in Windows. What's going on?
• My repeat format code doesn't repeat properly. What's the matter with it?
• No matter what I do I can only get six columns of output in my file. What am I doing wrong?
• How can I convert hexadecimal string values into numbers in IDL?
• How can I suppress the line feed character and print two values on the same line with different Print commands?
• How do I convert my CT data file to Hounsfield Units?
• Reading a double from a file produces float accuracy. Why?
• How do I read GRIB data into IDL?
• How can I left-justify text in column output?
• Is Dialog_Pickfile broken on UNIX machines?
• How can I make Dialog_Pickfile remember the last directory in which I opened an image file?
• How can I read calendar time data from a file?