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HDFView displays datasets in a two dimensional table, the TableView. The TableView allows you to view and change the values of a dataset of image. You can select rows and columns and plot the row/cloumn data in line plot. The current version of HDFView does not allow you to change data values of an HDF4 Vdata or an HDF5 compound dataset.
If a dataset has three or more dimensions you can only view two dimensions a time. Using the Dataset Selection Dialog , you may select any two dimensions of the dataset to display and a third dimension to flip the two dimension table along that dimension.
HDFView displays numerical datasets in a "spreadsheet", which shows the data values in a grid. A one-dimensional dataset is displayed as one column and number of rows of dimension size. A two-dimensional dataset is displayed as number of columns of the first dimension size and number of rows of the second dimension size, i.e. dim[0]=height and dim[1]=width by default. You can change the order of the dimensions using "Open As" command.
Opening an entire large dataset may cause an 'Out Of Memory Error', because the Java Virtual Machine cannot create the required objects. HDFView provides options to select a subset of a dataset for display. You can also select dimensions and order of dimension to display, e.g., to switch the columns and rows.
To make a selection, select a dataset from the tree and choose "Open As" command from the Object menu or the popup menu. The selection dialog appears. You can make a selection by draging the mouse on the preview image or entering the values of start, end and stride. The figure below shows that a subset is selected from a true color image with the size of 3796 x 3720.
By default, a scalar dataset (e.g., a dataset or SDS of numbers) is displayed in a Spreadsheet. You can also display a dataset as an image. To display a dataset in image, click the check box of image in the selection dialog and select a predefined color table the the dataset. This operation takes the data values of the dataset as values of an indexed array, i.e., as indexes into a palette. The default palette will be used to create the image from the dataset if it does not have an attached palette. If the data values are not integers or have a range outside 0 to 255, they are binned into 256 equally spaced intervals.
HDFView GUI uses common-sense indexing scheme for selecting rows and columns. If I want a subset that begins at i,j the START coordinates will starts at j, j instead of i-1, j-1.
Here is an example of 2D integer dataset of size 8 X 9.
11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |
31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 |
41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 |
51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 |
61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 |
71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 |
81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 |
The following are a few examples of subsets of the 2D int array
To flip a data sheet of a 3D dataset, you can use the "First", "Previous", "Next" or "Last" command on the tool bar.
The following figure shows how a 5D integer dataset of size of 10 x 20 x 30 x 40 x 50 is displayed. The data is displayed in spreadsheet of 40 X 50 (dim3 by dim4) of page 2 (dim2) cuting locations 2 at dim0 and 3 at dim1.
Let's use the previous example.
11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |
31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 |
41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 |
51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 |
61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 |
71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 |
81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 |
By default, the dataset is displayed at eight rows and nine columns.
Swap row and column dimensions to display the dataset as nine rows and eight columns. The order of data stays the same (counting from the location [0, 0], [0, 1], ... [2, 0], [2, 1], ...).
At some cases, we also want to transpose the data (changing the data order) when we swap the row and column dimensions. To transpose the data, select the normal dimension order (not the swapped order) and check the "Transpose" checkbox. For example,
Transpose the data to display the dataset as nine rows and eight columns. The order of data is also changed
You can also select fields/members to display. For contiguous selection, hold down the "Shift" key while click the first and last fields/members of your selection. For discontiguous selection, hold down the "Ctrl" key while click the fileds/members to select.
HDFView displays nested HDF5 compound dataset as flat list of members. The nested names are separated by ".". For example, if compound dataset "A" has the following nested structure,
A --> m01 A --> m02 A --> nest1 --> m11 A --> nest1 --> m12 A --> nest1 --> nest2 --> m21 A --> nest1 --> nest2 --> m22 i.e. A = { m01, m02, nest1{m11, m12, nest2{ m21, m22}}}The flat list of members of the compound dataset "A" will be {m01, m02, nest1.m11, nest1.m12, nest1.nest2.m21, nest1.nest2.m22}.
HDFView displays multi-dimension compound dataset as 2D table with nested sub-columns. The members are shown in sub-columns.
The following figure shows that data of five columns are displayed in five lines of different colors. The horizontal labels are the row index of the 100 data points. The vertical labels are the ten points of equal data range with the maximum and minimum of the column data. The line legend is drawn at the right of the line plot with column names and line colors.
Data type | Acceptable formats |
byte | -127 to 128 |
short | -32768 to 32767 |
int | -2147483648 to 2147483647 |
float, double | Numbers of the form "99.9" or "8", and "-9.9" or "-9", and ".9" or "-.9". Numeric overflow or underflow will be detected. |
string | A string longer than the stored value will be silently truncated when written to the file. |
unsigned byte | 0 to 255 |
unsigned short | 0 to 65535 |
unsigned int | 0 to 4294967295 |
Data values can be copied with "Copy" and "Paste". Data can be copied within a spreadsheet or between two spreadsheets. To copy data, you select the data cells to copy, then choose the "Copy Data" command from the "Object" menu. Select where to copy the data to and select the "Paste Data" command.
You can also copy and paste between HDFView and other applications. To copy external data from other application such as a text editor or MS Spreadsheet, select and copy data from the application, then paste the data to the HDFView TableView, vice versa.
You can also change values by predefined math functions. To change table values, you select the data area and choose "Math conversion" command from the table menu. A list of predefined mathematic functions are provided. Select a function and enter the function parameters. The values of selected data cells will be changed based on the mathematic function.
10 11 12 13 14 15 16 17 18 19 20 21and
10 11 12 13 14 15 16 17 18 19 20 21are the same.