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readdata

read numerical data from text files

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

readdata(fileID, n)

readdata(fileID, format, n)

readdata(fileID, format)

Parameters

fileID

-

symbol or string; file name or file descriptor of the data file

n

-

positive integer; specifies the number of columns of data

format

-

integer, float, or string or a list containing these names; specifies the format of the data that is read

Description

• 

The readdata function reads numeric data from a text file into Maple. The data in the file must consist of integers or floating-point values arranged in columns, separated by white space.

  

If only one column of data is read, the output is a list of the data. If more than one column is read, the output is a list of data corresponding to the rows of data in the file for the specified columns.

  

To read numerical data and store it in a Matrix or Vector, see ImportMatrix and ImportVector.

• 

The first form of the calling sequence for the readdata function reads n columns of numerical data in floating-point format from the file specified by fileID.

• 

The second and third calling sequence for readdata specify whether the data is read as integer, floating-point, or string data.  The format parameter must be one of integer, float, or string, or a list containing one or more of these.

  

Note: The procedure readline is used to read a line of data from the file and the data is extracted by using sscanf.

• 

While integers can be read as floating-point numbers, floating-point numbers should not be read in as integers.

• 

If a file name is specified (instead of a file descriptor), and the file is not already open, the file will be opened as a TEXT file in READ mode.  Furthermore, if a file name is specified, the file is closed when readdata returns.

  

Note: The writedata function is the corresponding function for writing numerical data into a file.

Examples

Suppose that the example file data contains the following data.

1

1

50

1

2

55

2

1

55

2

2

70

Read three columns of floating-point numbers from the file data.

readdatadata,3

1.,1.,50.,1.,2.,55.,2.,1.,55.,2.,2.,70.

(1)

Read three columns as integers.

readdatadata,integer,3

1,1,50,1,2,55,2,1,55,2,2,70

(2)

Read the first column of data as integers.

readdatadata,integer

1,1,2,2

(3)

Read the first column of data as floating-point numbers.

readdatadata,float

1.,1.,2.,2.

(4)

Read the first two columns as integers and the third column as floating-point numbers.

readdatadata,integer,integer,float

1,1,50.,1,2,55.,2,1,55.,2,2,70.

(5)

See Also

fopen

ImportMatrix

ImportVector

readline

sscanf

writedata

 


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