Return ''.join(.center(field) for field in self. Return ''.join(.rjust(field) for field in self.fields]) Return ''.join(.ljust(field) for field in self.fields]) Discussion: Sometimes we might want to generate a fixed width text file from an excel worksheet - for example to be an input into some legacy application. """ Returns line from list containing tuples of field values and lengths. This allows for selection of type of text alignment(left, right or centered.) class FixedWidthFieldLine(object):ĭef _init_(self, fields, justify = 'L'): I used Jarret Hardie's example and modified it slightly. It also doesn't check for instance values that are longer than their allotted width. Note this doesn't parse input, though you could easily override the constructor to take a string and parse the columns according to the field and field widths in fields. The resulting list of fields is then joined together by an empty string. It uses a list comprehension over the class-level fields attribute, looking up the instance value for each field by name, and then left-justifying it's output according to the columns. The _str_ method outputs these values as a string. There are correspondingly-named instance variables in the _init_ that are set to an empty string initially. It works by storing a class-level variable, fields which records the order in which each field should appear in the output, together with the number of columns that field should have. Return ''.join([getattr(self, field_name).ljust(width) What is a fixed width text file Data in a fixedwidth text file is arranged in rows and columns, with one entry per row.Each column has a fixed width, specified in characters, which determines the maximum amount of data it can contain. The snippet below may give you what you want class FixWidthFieldLine(object): I understand what you're looking for: some way to conveniently identify each part of the line by a simple variable, but output it padded to the correct width?.The user does not have sufficient permissions to access the file ( UnauthorizedAccessException). The path is too long ( PathTooLongException).
#Fixed width text file how to
What we weren’t sure of was how to make it work with a fixed-width file such as yours. We also knew, from previous experience, that this method worked really well with comma- or tab-separated values files. The specified file does not exist ( FileNotFoundException).Ī partial-trust situation in which the user does not have sufficient permissions to access the file. Interestingly, enough, we knew that Excel had a method named OpenText that could be used to open a text file as a spreadsheet. The exception message specifies the line causing the exception, while the ErrorLine property is assigned to the text contained in the line. The fixed-width text file has tabular data organized by starting location, number of variables, variable names, and variable widths. The following conditions may cause an exception:Ī row cannot be parsed using the specified format ( MalformedLineException). TextFieldParser("C:\TestFolder\test.log")Ĭatch ex As This example reads from the file test.log. Read a table of fixed width formatted data into a ame. Dim currentRow As String()Ĭlose the While and Using blocks with End While and End Using. If any lines are corrupted, report an error and continue parsing.
#Fixed width text file code
The following code defines the columns of text the first is 5 characters wide, the second 10, the third 11, and the fourth is of variable width. No delimiters are used to separate the fields in the file. Each column has a fixed width, specified in characters, which determines the maximum amount of data it can contain. Using Reader As New Microsoft.VisualBasic.įileIO.TextFieldParser("C:\TestFolder\test.log")ĭefine the TextFieldType property as FixedWidth, defining the width and format. What is a fixed width text file Data in a fixedwidth text file is arranged in rows and columns, with one entry per row. The following code creates the TextFieldParser named Reader and opens the file test.log. To parse a fixed-width text fileĬreate a new TextFieldParser. To specify that the field at the end has a variable width, define it to have a width less than or equal to zero. In a fixed-width text file, the field at the end can have a variable width. The TextFieldType property defines whether the parsed file is a delimited file or one that has fixed-width fields of text. The TextFieldParser object provides a way to easily and efficiently parse structured text files, such as logs.