versions.md
In igraph: Network Analysis and Visualization

we can't upgrade from 0.1.1 to 1.5.0, on the fly

Code
  oldsample_0_1_1()
Error <simpleError>
  This graph was created by igraph < 0.2.
    Upgrading this format is not supported, sorry.

we can't upgrade from 0.1.1 to 1.5.0, explicitly

Code
  upgrade_graph(g)
Error <simpleError>
  Don't know how to upgrade graph from version 0 to 4

we can't upgrade from 0.2 to 1.5.0, on the fly

Code
  oldsample_0_2()
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

we can't upgrade from 0.5 to 1.5.0, on the fly

Code
  oldsample_0_5()
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

we can't upgrade from 0.6 to 1.5.0, on the fly

Code
  oldsample_0_6()
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

we can upgrade from 1.0.0 to 1.5.0, on the fly

Code
  g <- oldsample_1_0_0()
  graph_version(g)
Output
  [1] 3
Code
  g
Message <simpleMessage>
  This graph was created by an old(er) igraph version.
    Call upgrade_graph() on it to use with the current igraph version
    For now we convert it on the fly...
Output
  IGRAPH D--- 3 3 -- Ring graph
  + attr: name (g/c), mutual (g/l), circular (g/l), bar (v/c), foo (e/c)
  + edges:
  [1] 1->2 2->3 3->1
Code
  graph_version(g)
Output
  [1] 4

reading of old igraph formats

Code
  s[["0.1.1"]]
Error <simpleError>
  This graph was created by igraph < 0.2.
    Upgrading this format is not supported, sorry.

Code
  s[["0.2"]]
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

Code
  s[["0.5"]]
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

Code
  s[["0.6"]]
Error <simpleError>
  This graph was created by a now unsupported old igraph version.
    Call upgrade_version() before using igraph functions on that object.

Code
  s[["1.0.0"]]
Message <simpleMessage>
  This graph was created by an old(er) igraph version.
    Call upgrade_graph() on it to use with the current igraph version
    For now we convert it on the fly...
Output
  IGRAPH D--- 3 3 -- Ring graph
  + attr: name (g/c), mutual (g/l), circular (g/l), bar (v/c), foo (e/c)
  + edges:
  [1] 1->2 2->3 3->1

Code
  s[["1.5.0"]]
Output
  IGRAPH D--- 3 3 -- Ring graph
  + attr: name (g/c), mutual (g/l), circular (g/l), bar (v/c), foo (e/c)
  + edges:
  [1] 1->2 2->3 3->1